From 5d946289efe1cd69fc680ab5efc16ac37a02a7db Mon Sep 17 00:00:00 2001
From: William Cheng <wing328hk@gmail.com>
Date: Wed, 28 Apr 2021 22:36:29 +0800
Subject: [PATCH 01/18] Bump OkHTTP dependency to latest in build.sbt (#9361)

---
 .../resources/Java/libraries/okhttp-gson/build.sbt.mustache   | 4 ++--
 .../petstore/java/okhttp-gson-dynamicOperations/build.sbt     | 4 ++--
 .../petstore/java/okhttp-gson-parcelableModel/build.sbt       | 4 ++--
 samples/client/petstore/java/okhttp-gson/build.sbt            | 4 ++--
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.sbt.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.sbt.mustache
index a14047e79984..8979b10a7f8c 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.sbt.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.sbt.mustache
@@ -10,8 +10,8 @@ lazy val root = (project in file(".")).
     resolvers += Resolver.mavenLocal,
     libraryDependencies ++= Seq(
       "io.swagger" % "swagger-annotations" % "1.5.24",
-      "com.squareup.okhttp3" % "okhttp" % "3.14.7",
-      "com.squareup.okhttp3" % "logging-interceptor" % "3.14.7",
+      "com.squareup.okhttp3" % "okhttp" % "4.9.1",
+      "com.squareup.okhttp3" % "logging-interceptor" % "4.9.1",
       "com.google.code.gson" % "gson" % "2.8.6",
       "org.apache.commons" % "commons-lang3" % "3.10",
       {{#hasOAuthMethods}}
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.sbt b/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.sbt
index 289532fdd680..020460f4527d 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.sbt
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.sbt
@@ -10,8 +10,8 @@ lazy val root = (project in file(".")).
     resolvers += Resolver.mavenLocal,
     libraryDependencies ++= Seq(
       "io.swagger" % "swagger-annotations" % "1.5.24",
-      "com.squareup.okhttp3" % "okhttp" % "3.14.7",
-      "com.squareup.okhttp3" % "logging-interceptor" % "3.14.7",
+      "com.squareup.okhttp3" % "okhttp" % "4.9.1",
+      "com.squareup.okhttp3" % "logging-interceptor" % "4.9.1",
       "com.google.code.gson" % "gson" % "2.8.6",
       "org.apache.commons" % "commons-lang3" % "3.10",
       "org.apache.oltu.oauth2" % "org.apache.oltu.oauth2.client" % "1.0.1",
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/build.sbt b/samples/client/petstore/java/okhttp-gson-parcelableModel/build.sbt
index d3bf50f4d7f6..c36bbc5ca081 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/build.sbt
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/build.sbt
@@ -10,8 +10,8 @@ lazy val root = (project in file(".")).
     resolvers += Resolver.mavenLocal,
     libraryDependencies ++= Seq(
       "io.swagger" % "swagger-annotations" % "1.5.24",
-      "com.squareup.okhttp3" % "okhttp" % "3.14.7",
-      "com.squareup.okhttp3" % "logging-interceptor" % "3.14.7",
+      "com.squareup.okhttp3" % "okhttp" % "4.9.1",
+      "com.squareup.okhttp3" % "logging-interceptor" % "4.9.1",
       "com.google.code.gson" % "gson" % "2.8.6",
       "org.apache.commons" % "commons-lang3" % "3.10",
       "org.apache.oltu.oauth2" % "org.apache.oltu.oauth2.client" % "1.0.1",
diff --git a/samples/client/petstore/java/okhttp-gson/build.sbt b/samples/client/petstore/java/okhttp-gson/build.sbt
index ae1791028e0f..6dfd0d7f733b 100644
--- a/samples/client/petstore/java/okhttp-gson/build.sbt
+++ b/samples/client/petstore/java/okhttp-gson/build.sbt
@@ -10,8 +10,8 @@ lazy val root = (project in file(".")).
     resolvers += Resolver.mavenLocal,
     libraryDependencies ++= Seq(
       "io.swagger" % "swagger-annotations" % "1.5.24",
-      "com.squareup.okhttp3" % "okhttp" % "3.14.7",
-      "com.squareup.okhttp3" % "logging-interceptor" % "3.14.7",
+      "com.squareup.okhttp3" % "okhttp" % "4.9.1",
+      "com.squareup.okhttp3" % "logging-interceptor" % "4.9.1",
       "com.google.code.gson" % "gson" % "2.8.6",
       "org.apache.commons" % "commons-lang3" % "3.10",
       "org.apache.oltu.oauth2" % "org.apache.oltu.oauth2.client" % "1.0.1",

From 18cdb36d3e4999198544ae64729f20613a228098 Mon Sep 17 00:00:00 2001
From: William Cheng <wing328hk@gmail.com>
Date: Thu, 29 Apr 2021 10:23:55 +0800
Subject: [PATCH 02/18] [Test] Migrate samples from 2.0 Spec to 3.0 spec
 (#9347)

* nim petstore to use 3.0 spec

* ktorm to use 3.0 spec

* update c petstore to use 3.0 spec

* Revert "update c petstore to use 3.0 spec"

This reverts commit a8ff0517bacc52fd9ac945f5812a8c12294fc410.
---
 bin/configs/ktorm-schema.yaml                    |  4 ++--
 bin/configs/nim.yaml                             |  2 +-
 .../petstore/nim/petstore/apis/api_pet.nim       | 12 ++++++++----
 .../petstore/nim/petstore/apis/api_store.nim     |  4 ++--
 .../petstore/nim/petstore/apis/api_user.nim      | 16 ++++++++--------
 5 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/bin/configs/ktorm-schema.yaml b/bin/configs/ktorm-schema.yaml
index aff895cb279b..d3c5beb9a33b 100644
--- a/bin/configs/ktorm-schema.yaml
+++ b/bin/configs/ktorm-schema.yaml
@@ -1,7 +1,7 @@
 generatorName: ktorm-schema
 outputDir: samples/schema/petstore/ktorm
-inputSpec: modules/openapi-generator/src/test/resources/2_0/petstore.yaml
+inputSpec: modules/openapi-generator/src/test/resources/3_0/petstore.yaml
 templateDir: modules/openapi-generator/src/main/resources/ktorm-schema
 additionalProperties:
   hideGenerationTimestamp: true
-  importModelPackageName: org.openapitools.client.models
\ No newline at end of file
+  importModelPackageName: org.openapitools.client.models
diff --git a/bin/configs/nim.yaml b/bin/configs/nim.yaml
index 136a92764c3c..13a27a6b764c 100644
--- a/bin/configs/nim.yaml
+++ b/bin/configs/nim.yaml
@@ -1,6 +1,6 @@
 generatorName: nim
 outputDir: samples/client/petstore/nim
-inputSpec: modules/openapi-generator/src/test/resources/2_0/petstore.yaml
+inputSpec: modules/openapi-generator/src/test/resources/3_0/petstore.yaml
 templateDir: modules/openapi-generator/src/main/resources/nim-client
 additionalProperties:
   packageName: petstore
diff --git a/samples/client/petstore/nim/petstore/apis/api_pet.nim b/samples/client/petstore/nim/petstore/apis/api_pet.nim
index 3644e392340a..b2f77c2bdbb8 100644
--- a/samples/client/petstore/nim/petstore/apis/api_pet.nim
+++ b/samples/client/petstore/nim/petstore/apis/api_pet.nim
@@ -39,10 +39,12 @@ template constructResult[T](response: Response): untyped =
     (none(T.typedesc), response)
 
 
-proc addPet*(httpClient: HttpClient, body: Pet): Response =
+proc addPet*(httpClient: HttpClient, pet: Pet): (Option[Pet], Response) =
   ## Add a new pet to the store
   httpClient.headers["Content-Type"] = "application/json"
-  httpClient.post(basepath & "/pet", $(%body))
+
+  let response = httpClient.post(basepath & "/pet", $(%pet))
+  constructResult[Pet](response)
 
 
 proc deletePet*(httpClient: HttpClient, petId: int64, apiKey: string): Response =
@@ -78,10 +80,12 @@ proc getPetById*(httpClient: HttpClient, petId: int64): (Option[Pet], Response)
   constructResult[Pet](response)
 
 
-proc updatePet*(httpClient: HttpClient, body: Pet): Response =
+proc updatePet*(httpClient: HttpClient, pet: Pet): (Option[Pet], Response) =
   ## Update an existing pet
   httpClient.headers["Content-Type"] = "application/json"
-  httpClient.put(basepath & "/pet", $(%body))
+
+  let response = httpClient.put(basepath & "/pet", $(%pet))
+  constructResult[Pet](response)
 
 
 proc updatePetWithForm*(httpClient: HttpClient, petId: int64, name: string, status: string): Response =
diff --git a/samples/client/petstore/nim/petstore/apis/api_store.nim b/samples/client/petstore/nim/petstore/apis/api_store.nim
index 3c518e8dd31a..a2f018b7cf3d 100644
--- a/samples/client/petstore/nim/petstore/apis/api_store.nim
+++ b/samples/client/petstore/nim/petstore/apis/api_store.nim
@@ -57,10 +57,10 @@ proc getOrderById*(httpClient: HttpClient, orderId: int64): (Option[Order], Resp
   constructResult[Order](response)
 
 
-proc placeOrder*(httpClient: HttpClient, body: Order): (Option[Order], Response) =
+proc placeOrder*(httpClient: HttpClient, order: Order): (Option[Order], Response) =
   ## Place an order for a pet
   httpClient.headers["Content-Type"] = "application/json"
 
-  let response = httpClient.post(basepath & "/store/order", $(%body))
+  let response = httpClient.post(basepath & "/store/order", $(%order))
   constructResult[Order](response)
 
diff --git a/samples/client/petstore/nim/petstore/apis/api_user.nim b/samples/client/petstore/nim/petstore/apis/api_user.nim
index 87bef06818e4..618477db5954 100644
--- a/samples/client/petstore/nim/petstore/apis/api_user.nim
+++ b/samples/client/petstore/nim/petstore/apis/api_user.nim
@@ -38,22 +38,22 @@ template constructResult[T](response: Response): untyped =
     (none(T.typedesc), response)
 
 
-proc createUser*(httpClient: HttpClient, body: User): Response =
+proc createUser*(httpClient: HttpClient, user: User): Response =
   ## Create user
   httpClient.headers["Content-Type"] = "application/json"
-  httpClient.post(basepath & "/user", $(%body))
+  httpClient.post(basepath & "/user", $(%user))
 
 
-proc createUsersWithArrayInput*(httpClient: HttpClient, body: seq[User]): Response =
+proc createUsersWithArrayInput*(httpClient: HttpClient, user: seq[User]): Response =
   ## Creates list of users with given input array
   httpClient.headers["Content-Type"] = "application/json"
-  httpClient.post(basepath & "/user/createWithArray", $(%body))
+  httpClient.post(basepath & "/user/createWithArray", $(%user))
 
 
-proc createUsersWithListInput*(httpClient: HttpClient, body: seq[User]): Response =
+proc createUsersWithListInput*(httpClient: HttpClient, user: seq[User]): Response =
   ## Creates list of users with given input array
   httpClient.headers["Content-Type"] = "application/json"
-  httpClient.post(basepath & "/user/createWithList", $(%body))
+  httpClient.post(basepath & "/user/createWithList", $(%user))
 
 
 proc deleteUser*(httpClient: HttpClient, username: string): Response =
@@ -84,8 +84,8 @@ proc logoutUser*(httpClient: HttpClient): Response =
   httpClient.get(basepath & "/user/logout")
 
 
-proc updateUser*(httpClient: HttpClient, username: string, body: User): Response =
+proc updateUser*(httpClient: HttpClient, username: string, user: User): Response =
   ## Updated user
   httpClient.headers["Content-Type"] = "application/json"
-  httpClient.put(basepath & fmt"/user/{username}", $(%body))
+  httpClient.put(basepath & fmt"/user/{username}", $(%user))
 

From dbb42f90278c92d7dde0627a4647f8082dfa13d5 Mon Sep 17 00:00:00 2001
From: Anders Aaen Springborg <aaspringborg@gmail.com>
Date: Thu, 29 Apr 2021 12:23:13 +0200
Subject: [PATCH 03/18] [BUG] new.sh fix generator type , issue #9320 (#9321)

* generation type on  template dir path

* remove gen_type from template and resources
---
 new.sh | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/new.sh b/new.sh
index 12cfec8cb579..7d33be840e55 100755
--- a/new.sh
+++ b/new.sh
@@ -178,7 +178,7 @@ public class ${lang_classname} extends DefaultCodegen implements CodegenConfig {
         outputFolder = "generated-code" + File.separator + "${gen_name_camel}";
         modelTemplateFiles.put("model.mustache", ".zz");
         apiTemplateFiles.put("api.mustache", ".zz");
-        embeddedTemplateDir = templateDir = "${gen_name_camel}-${gen_type}";
+        embeddedTemplateDir = templateDir = "${gen_name_camel}";
         apiPackage = "Apis";
         modelPackage = "Models";
         supportingFiles.add(new SupportingFile("README.mustache", "", "README.md"));
@@ -191,17 +191,17 @@ EOF
 echo -e "\norg.openapitools.codegen.languages.${lang_classname}" >> "${root}/modules/openapi-generator/src/main/resources/META-INF/services/org.openapitools.codegen.CodegenConfig"
 
 # Step 3: Create resource files
-mkdir -p "${root}/modules/openapi-generator/src/main/resources/${gen_name_camel}-${gen_type}"
-echo "Creating modules/openapi-generator/src/main/resources/${gen_name_camel}-${gen_type}/README.mustache" && \
-    touch "${root}/modules/openapi-generator/src/main/resources/${gen_name_camel}-${gen_type}/README.mustache"
-echo "Creating modules/openapi-generator/src/main/resources/${gen_name_camel}-${gen_type}/model.mustache" && \
-    touch "${root}/modules/openapi-generator/src/main/resources/${gen_name_camel}-${gen_type}/model.mustache"
-echo "Creating modules/openapi-generator/src/main/resources/${gen_name_camel}-${gen_type}/api.mustache" && \
-    touch "${root}/modules/openapi-generator/src/main/resources/${gen_name_camel}-${gen_type}/api.mustache"
+mkdir -p "${root}/modules/openapi-generator/src/main/resources/${gen_name_camel}"
+echo "Creating modules/openapi-generator/src/main/resources/${gen_name_camel}/README.mustache" && \
+    touch "${root}/modules/openapi-generator/src/main/resources/${gen_name_camel}/README.mustache"
+echo "Creating modules/openapi-generator/src/main/resources/${gen_name_camel}/model.mustache" && \
+    touch "${root}/modules/openapi-generator/src/main/resources/${gen_name_camel}/model.mustache"
+echo "Creating modules/openapi-generator/src/main/resources/${gen_name_camel}/api.mustache" && \
+    touch "${root}/modules/openapi-generator/src/main/resources/${gen_name_camel}/api.mustache"
 
 # Step 4: Create generation config scripts
-echo "Creating bin/configs/${gen_name_camel}-${gen_type}-petstore-new.yaml"
-cat > "${root}/bin/configs/${gen_name_camel}-${gen_type}-petstore-new.yaml"<<EOF
+echo "Creating bin/configs/${gen_name_camel}-petstore-new.yaml"
+cat > "${root}/bin/configs/${gen_name_camel}-petstore-new.yaml"<<EOF
 generatorName: ${gen_name_camel}
 outputDir: samples/${gen_type}/petstore/${gen_name_camel_path}
 inputSpec: modules/openapi-generator/src/test/resources/3_0/petstore.yaml

From ebc1d7bd9519d19fe59bc9101437522c6a0ca6af Mon Sep 17 00:00:00 2001
From: ex0ns <ex0ns@users.noreply.github.com>
Date: Thu, 29 Apr 2021 12:51:30 +0200
Subject: [PATCH 04/18] [scala][akka] Update dependencies for scala 2.13 in
 scala-akka (#8624)

* [scala][akka] Update dependencies for scala 2.13

* Update pom.mustache to support multiple scala's version

* Update pom.xml

* Scala cross build 2.12 and 2.13

* Update version. Migrate to sbt

* Remove space

* Add pom.xml back
---
 .../languages/ScalaAkkaClientCodegen.java     |  3 +-
 .../scala-akka-client/apiInvoker.mustache     | 31 +++++++++++--------
 .../scala-akka-client/apiSettings.mustache    | 15 +++++++--
 .../scala-akka-client/build.sbt.mustache      | 24 ++++++++------
 .../resources/scala-akka-client/pom.mustache  | 30 +++++++++++-------
 .../project/build.properties.mustache         |  1 +
 .../scalaakka/ScalaAkkaClientCodegenTest.java |  4 +--
 .../scala-akka/.openapi-generator/FILES       |  1 +
 samples/client/petstore/scala-akka/build.sbt  | 24 ++++++++------
 samples/client/petstore/scala-akka/pom.xml    | 30 +++++++++++-------
 .../scala-akka/project/build.properties       |  1 +
 .../openapitools/client/core/ApiInvoker.scala | 31 +++++++++++--------
 .../client/core/ApiSettings.scala             | 15 +++++++--
 .../src/test/scala/PetApiTest.scala           | 24 +++++++-------
 14 files changed, 143 insertions(+), 91 deletions(-)
 create mode 100644 modules/openapi-generator/src/main/resources/scala-akka-client/project/build.properties.mustache
 create mode 100644 samples/client/petstore/scala-akka/project/build.properties

diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ScalaAkkaClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ScalaAkkaClientCodegen.java
index 138e9bf9c1d8..a5e293c9879d 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ScalaAkkaClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ScalaAkkaClientCodegen.java
@@ -166,8 +166,8 @@ public void processOpts() {
         additionalProperties.put(CodegenConstants.INVOKER_PACKAGE, invokerPackage);
 
         supportingFiles.add(new SupportingFile("README.mustache", "", "README.md"));
-        supportingFiles.add(new SupportingFile("pom.mustache", "", "pom.xml"));
         supportingFiles.add(new SupportingFile("build.sbt.mustache", "", "build.sbt"));
+        supportingFiles.add(new SupportingFile("pom.mustache", "", "pom.xml"));
         supportingFiles.add(new SupportingFile("reference.mustache", resourcesFolder, "reference.conf"));
         final String invokerFolder = (sourceFolder + File.separator + invokerPackage).replace(".", File.separator);
         supportingFiles.add(new SupportingFile("apiRequest.mustache", invokerFolder, "ApiRequest.scala"));
@@ -175,6 +175,7 @@ public void processOpts() {
         supportingFiles.add(new SupportingFile("requests.mustache", invokerFolder, "requests.scala"));
         supportingFiles.add(new SupportingFile("apiSettings.mustache", invokerFolder, "ApiSettings.scala"));
         final String apiFolder = (sourceFolder + File.separator + apiPackage).replace(".", File.separator);
+        supportingFiles.add(new SupportingFile("project/build.properties.mustache", "project", "build.properties"));
         supportingFiles.add(new SupportingFile("enumsSerializers.mustache", apiFolder, "EnumsSerializers.scala"));
         supportingFiles.add(new SupportingFile("serializers.mustache", invokerFolder, "Serializers.scala"));
     }
diff --git a/modules/openapi-generator/src/main/resources/scala-akka-client/apiInvoker.mustache b/modules/openapi-generator/src/main/resources/scala-akka-client/apiInvoker.mustache
index 8c81b0b2d8b5..a82135170c43 100644
--- a/modules/openapi-generator/src/main/resources/scala-akka-client/apiInvoker.mustache
+++ b/modules/openapi-generator/src/main/resources/scala-akka-client/apiInvoker.mustache
@@ -18,6 +18,7 @@ import de.heikoseeberger.akkahttpjson4s.Json4sSupport
 import org.json4s._
 import org.json4s.jackson.JsonMethods._
 import org.json4s.jackson.Serialization
+import scala.collection.compat._
 
 import scala.collection.immutable
 import scala.concurrent.{ ExecutionContext, ExecutionContextExecutor, Future }
@@ -86,7 +87,7 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
 
   private val http = Http()
 
-  val CompressionFilter: HttpMessage ⇒ Boolean = (msg: HttpMessage) =>
+  val CompressionFilter: HttpMessage => Boolean = (msg: HttpMessage) =>
     Seq(
       { _: HttpMessage => settings.compressionEnabled },
       Encoder.DefaultFilter,
@@ -115,7 +116,7 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
   private def headers(headers: Map[String, Any]): immutable.Seq[HttpHeader] =
     headers.asFormattedParams
       .map { case (name, value) => RawHeader(name, value.toString) }
-      .to[immutable.Seq]
+      .to(immutable.Seq)
 
 
   private def bodyPart(name: String, value: Any): BodyPart = {
@@ -147,9 +148,9 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
           case MediaTypes.`multipart/form-data` =>
             Multipart.FormData(Source(params.toList.map { case (name, value) => bodyPart(name, value) }))
           case MediaTypes.`application/x-www-form-urlencoded` =>
-            FormData(params.mapValues(_.toString))
+            FormData(params.view.mapValues(_.toString).toMap)
           case _: MediaType => // Default : application/x-www-form-urlencoded.
-            FormData(params.mapValues(_.toString))
+            FormData(params.view.mapValues(_.toString).toMap)
         }
       )
   }
@@ -187,7 +188,9 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
         params + (keyName -> key.value)
       case (params, _) => params
     }.asFormattedParams
+      .view
       .mapValues(_.toString)
+      .toMap
       .foldRight[Query](Uri.Query.Empty) {
       case ((name, value), acc) => acc.+:(name, value)
     }
@@ -196,7 +199,9 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
   def makeUri(r: ApiRequest[_]): Uri = {
     val opPath = r.operationPath.replaceAll("\\{format\\}", "json")
     val opPathWithParams = r.pathParams.asFormattedParams
+      .view
       .mapValues(_.toString)
+      .toMap
       .foldLeft(opPath) {
         case (path, (name, value)) => path.replaceAll(s"\\{$name\\}", value)
       }
@@ -213,13 +218,13 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
     http
       .singleRequest(request)
       .map { response =>
-        val decoder: Coder with StreamDecoder = response.encoding match {
-          case HttpEncodings.gzip ⇒
-            Gzip
-          case HttpEncodings.deflate ⇒
-            Deflate
-          case HttpEncodings.identity ⇒
-            NoCoding
+        val decoder: Decoder with Decoder = response.encoding match {
+          case HttpEncodings.gzip =>
+            Coders.Gzip
+          case HttpEncodings.deflate =>
+            Coders.Deflate
+          case HttpEncodings.identity =>
+            Coders.NoCoding
           case HttpEncoding(encoding) =>
             throw new IllegalArgumentException(s"Unsupported encoding: $encoding")
         }
@@ -247,13 +252,13 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
     request
       .responseForCode(response.status.intValue) match {
       case Some((Manifest.Unit, state: ResponseState)) =>
-        Future(responseForState(state, Unit).asInstanceOf[ApiResponse[T]])
+        Future(responseForState(state, ()).asInstanceOf[ApiResponse[T]])
       case Some((manifest, state: ResponseState)) if manifest == mf =>
         implicit val m: Unmarshaller[HttpEntity, T] = unmarshaller[T](mf, serialization, formats)
         Unmarshal(response.entity)
           .to[T]
           .recoverWith {
-            case e ⇒ throw ApiError(response.status.intValue, s"Unable to unmarshall content to [$manifest]", Some(response.entity.toString), e)
+            case e => throw ApiError(response.status.intValue, s"Unable to unmarshall content to [$manifest]", Some(response.entity.toString), e)
           }
           .map(value => responseForState(state, value))
       case None | Some(_) =>
diff --git a/modules/openapi-generator/src/main/resources/scala-akka-client/apiSettings.mustache b/modules/openapi-generator/src/main/resources/scala-akka-client/apiSettings.mustache
index d5856ccc17d1..22f56080b01c 100644
--- a/modules/openapi-generator/src/main/resources/scala-akka-client/apiSettings.mustache
+++ b/modules/openapi-generator/src/main/resources/scala-akka-client/apiSettings.mustache
@@ -3,12 +3,12 @@ package {{invokerPackage}}
 
 import java.util.concurrent.TimeUnit
 
-import akka.actor.{ ExtendedActorSystem, Extension, ExtensionKey }
+import akka.actor.{ActorSystem, ExtendedActorSystem, Extension, ExtensionId, ExtensionIdProvider}
 import akka.http.scaladsl.model.StatusCodes.CustomStatusCode
 import akka.http.scaladsl.model.headers.RawHeader
 import com.typesafe.config.Config
 
-import scala.collection.JavaConverters._
+import scala.jdk.CollectionConverters._
 import scala.concurrent.duration.FiniteDuration
 
 class ApiSettings(config: Config) extends Extension {
@@ -32,4 +32,13 @@ class ApiSettings(config: Config) extends Extension {
   }
 }
 
-object ApiSettings extends ExtensionKey[ApiSettings]
+object ApiSettings extends ExtensionId[ApiSettings] with ExtensionIdProvider {
+
+  override def lookup = ApiSettings
+
+  override def createExtension(system: ExtendedActorSystem): ApiSettings =
+    new ApiSettings(system)
+
+  // needed to get the type right when used from Java
+  override def get(system: ActorSystem): ApiSettings = super.get(system)
+}
diff --git a/modules/openapi-generator/src/main/resources/scala-akka-client/build.sbt.mustache b/modules/openapi-generator/src/main/resources/scala-akka-client/build.sbt.mustache
index c26dae841c7b..e4c21c19d0c0 100644
--- a/modules/openapi-generator/src/main/resources/scala-akka-client/build.sbt.mustache
+++ b/modules/openapi-generator/src/main/resources/scala-akka-client/build.sbt.mustache
@@ -1,22 +1,26 @@
 version := "{{artifactVersion}}"
 name := "{{artifactId}}"
 organization := "{{groupId}}"
-scalaVersion := "2.12.8"
+
+scalaVersion := "2.12.13"
+crossScalaVersions := Seq(scalaVersion.value, "2.13.4")
+
 
 libraryDependencies ++= Seq(
-  "com.typesafe" % "config" % "1.3.3",
-  "com.typesafe.akka" %% "akka-actor" % "2.5.21",
-  "com.typesafe.akka" %% "akka-stream" % "2.5.21",
-  "com.typesafe.akka" %% "akka-http" % "10.1.7",
+  "com.typesafe" % "config" % "1.4.1",
+  "com.typesafe.akka" %% "akka-actor" % "2.6.12",
+  "com.typesafe.akka" %% "akka-stream" % "2.6.12",
+  "com.typesafe.akka" %% "akka-http" % "10.2.3",
 {{#joda}}
   "joda-time" % "joda-time" % "2.10.1",
 {{/joda}}
-  "org.json4s" %% "json4s-jackson" % "3.6.5",
-  "org.json4s" %% "json4s-ext" % "3.6.5",
-  "de.heikoseeberger" %% "akka-http-json4s" % "1.25.2",
+  "org.json4s" %% "json4s-jackson" % "3.6.7",
+  "org.json4s" %% "json4s-ext" % "3.6.7",
+  "de.heikoseeberger" %% "akka-http-json4s" % "1.27.0",
+  "org.scala-lang.modules" %% "scala-collection-compat" % "2.4.1",
   // test dependencies
-  "org.scalatest" %% "scalatest" % "3.0.5" % "test",
-  "junit" % "junit" % "4.13.1" % "test"
+  "org.scalatest"     %% "scalatest"  % "3.2.3"   % "test",
+  "org.scalatestplus" %% "junit-4-13" % "3.2.3.0" % "test"
 )
 
 resolvers ++= Seq(Resolver.mavenLocal)
diff --git a/modules/openapi-generator/src/main/resources/scala-akka-client/pom.mustache b/modules/openapi-generator/src/main/resources/scala-akka-client/pom.mustache
index 78cbec12128a..e82df0c17b9a 100644
--- a/modules/openapi-generator/src/main/resources/scala-akka-client/pom.mustache
+++ b/modules/openapi-generator/src/main/resources/scala-akka-client/pom.mustache
@@ -15,18 +15,19 @@
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
 
     <java.version>1.8</java.version>
-    <scala.version>2.12.8</scala.version>
-    <json4s.jackson.version>3.5.3</json4s.jackson.version>
-    <json4s.ext.version>3.2.11</json4s.ext.version>
-    <akka.version>2.5.21</akka.version>
-    <akka.http.version>10.1.7</akka.http.version>
+    <scala.version>2.12.13</scala.version>
+    <json4s.jackson.version>3.6.7</json4s.jackson.version>
+    <json4s.ext.version>3.6.7</json4s.ext.version>
+    <akka.version>2.6.12</akka.version>
+    <akka.http.version>10.2.3</akka.http.version>
 {{#joda}}
     <joda.time.version>2.10.1</joda.time.version>
 {{/joda}}
-    <typesafeconfig.version>1.3.3</typesafeconfig.version>
-    <akka.http.json4s.version>1.25.2</akka.http.json4s.version>
-    <junit.version>4.13.1</junit.version>
-    <scala.test.version>3.0.5</scala.test.version>
+    <typesafeconfig.version>1.4.1</typesafeconfig.version>
+    <akka.http.json4s.version>1.27.0</akka.http.json4s.version>
+    <scala.compat.version>2.4.1</scala.compat.version>
+    <scala.test.version>3.2.3</scala.test.version>
+    <scala.test.plus.version>3.2.3.0</scala.test.plus.version>
 
     <scala.maven.plugin.version>3.3.1</scala.maven.plugin.version>
   </properties>
@@ -80,6 +81,11 @@
       <artifactId>akka-http-json4s_2.12</artifactId>
       <version>${akka.http.json4s.version}</version>
     </dependency>
+  <dependency>
+      <groupId>org.scala-lang.modules</groupId>
+      <artifactId>scala-collection-compat_2.12</artifactId>
+      <version>${scala.compat.version}</version>
+  </dependency>
 
     <!--test dependencies-->
     <dependency>
@@ -89,9 +95,9 @@
       <scope>test</scope>
     </dependency>
     <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <version>${junit.version}</version>
+      <groupId>org.scalatestplus</groupId>
+      <artifactId>junit-4-13_2.12</artifactId>
+      <version>${scala.test.plus.version}</version>
       <scope>test</scope>
     </dependency>
   </dependencies>
diff --git a/modules/openapi-generator/src/main/resources/scala-akka-client/project/build.properties.mustache b/modules/openapi-generator/src/main/resources/scala-akka-client/project/build.properties.mustache
new file mode 100644
index 000000000000..dc07aed85e00
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/scala-akka-client/project/build.properties.mustache
@@ -0,0 +1 @@
+sbt.version=1.3.10
\ No newline at end of file
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalaakka/ScalaAkkaClientCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalaakka/ScalaAkkaClientCodegenTest.java
index d78b487d2860..4304e092bb16 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalaakka/ScalaAkkaClientCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalaakka/ScalaAkkaClientCodegenTest.java
@@ -472,7 +472,7 @@ public void mainPackageTest() throws Exception {
         Generator gen = generator.opts(clientOptInput);
         List<File> files = gen.generate();
 
-        Assert.assertEquals(files.size(), 15);
+        Assert.assertEquals(files.size(), 16);
 
         TestUtils.ensureContainsFile(files, output, "src/main/scala/hello/world/model/SomeObj.scala");
         TestUtils.ensureContainsFile(files, output, "src/main/scala/hello/world/core/ApiSettings.scala");
@@ -509,7 +509,7 @@ public void overridePackagesTest() throws Exception {
         Generator gen = generator.opts(clientOptInput);
 
         List<File> files = gen.generate();
-        Assert.assertEquals(files.size(), 15);
+        Assert.assertEquals(files.size(), 16);
 
         TestUtils.ensureContainsFile(files, output, "src/main/scala/hello/world/model/package/SomeObj.scala");
         TestUtils.ensureContainsFile(files, output, "src/main/scala/hello/world/package/invoker/ApiSettings.scala");
diff --git a/samples/client/petstore/scala-akka/.openapi-generator/FILES b/samples/client/petstore/scala-akka/.openapi-generator/FILES
index 8d22043b5a91..2cd9737cf183 100644
--- a/samples/client/petstore/scala-akka/.openapi-generator/FILES
+++ b/samples/client/petstore/scala-akka/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 README.md
 build.sbt
+project/build.properties
 src/main/resources/reference.conf
 src/main/scala/org/openapitools/client/api/EnumsSerializers.scala
 src/main/scala/org/openapitools/client/api/PetApi.scala
diff --git a/samples/client/petstore/scala-akka/build.sbt b/samples/client/petstore/scala-akka/build.sbt
index 038757790a5a..e9915b07f85f 100644
--- a/samples/client/petstore/scala-akka/build.sbt
+++ b/samples/client/petstore/scala-akka/build.sbt
@@ -1,19 +1,23 @@
 version := "1.0.0"
 name := "scala-akka-petstore-client"
 organization := "org.openapitools"
-scalaVersion := "2.12.8"
+
+scalaVersion := "2.12.13"
+crossScalaVersions := Seq(scalaVersion.value, "2.13.4")
+
 
 libraryDependencies ++= Seq(
-  "com.typesafe" % "config" % "1.3.3",
-  "com.typesafe.akka" %% "akka-actor" % "2.5.21",
-  "com.typesafe.akka" %% "akka-stream" % "2.5.21",
-  "com.typesafe.akka" %% "akka-http" % "10.1.7",
-  "org.json4s" %% "json4s-jackson" % "3.6.5",
-  "org.json4s" %% "json4s-ext" % "3.6.5",
-  "de.heikoseeberger" %% "akka-http-json4s" % "1.25.2",
+  "com.typesafe" % "config" % "1.4.1",
+  "com.typesafe.akka" %% "akka-actor" % "2.6.12",
+  "com.typesafe.akka" %% "akka-stream" % "2.6.12",
+  "com.typesafe.akka" %% "akka-http" % "10.2.3",
+  "org.json4s" %% "json4s-jackson" % "3.6.7",
+  "org.json4s" %% "json4s-ext" % "3.6.7",
+  "de.heikoseeberger" %% "akka-http-json4s" % "1.27.0",
+  "org.scala-lang.modules" %% "scala-collection-compat" % "2.4.1",
   // test dependencies
-  "org.scalatest" %% "scalatest" % "3.0.5" % "test",
-  "junit" % "junit" % "4.13.1" % "test"
+  "org.scalatest"     %% "scalatest"  % "3.2.3"   % "test",
+  "org.scalatestplus" %% "junit-4-13" % "3.2.3.0" % "test"
 )
 
 resolvers ++= Seq(Resolver.mavenLocal)
diff --git a/samples/client/petstore/scala-akka/pom.xml b/samples/client/petstore/scala-akka/pom.xml
index 42e08693b641..0f93bcb372b4 100644
--- a/samples/client/petstore/scala-akka/pom.xml
+++ b/samples/client/petstore/scala-akka/pom.xml
@@ -15,15 +15,16 @@
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
 
     <java.version>1.8</java.version>
-    <scala.version>2.12.8</scala.version>
-    <json4s.jackson.version>3.5.3</json4s.jackson.version>
-    <json4s.ext.version>3.2.11</json4s.ext.version>
-    <akka.version>2.5.21</akka.version>
-    <akka.http.version>10.1.7</akka.http.version>
-    <typesafeconfig.version>1.3.3</typesafeconfig.version>
-    <akka.http.json4s.version>1.25.2</akka.http.json4s.version>
-    <junit.version>4.13</junit.version>
-    <scala.test.version>3.0.5</scala.test.version>
+    <scala.version>2.12.13</scala.version>
+    <json4s.jackson.version>3.6.7</json4s.jackson.version>
+    <json4s.ext.version>3.6.7</json4s.ext.version>
+    <akka.version>2.6.12</akka.version>
+    <akka.http.version>10.2.3</akka.http.version>
+    <typesafeconfig.version>1.4.1</typesafeconfig.version>
+    <akka.http.json4s.version>1.27.0</akka.http.json4s.version>
+    <scala.compat.version>2.4.1</scala.compat.version>
+    <scala.test.version>3.2.3</scala.test.version>
+    <scala.test.plus.version>3.2.3.0</scala.test.plus.version>
 
     <scala.maven.plugin.version>3.3.1</scala.maven.plugin.version>
   </properties>
@@ -70,6 +71,11 @@
       <artifactId>akka-http-json4s_2.12</artifactId>
       <version>${akka.http.json4s.version}</version>
     </dependency>
+    <dependency>
+      <groupId>org.scala-lang.modules</groupId>
+      <artifactId>scala-collection-compat_2.12</artifactId>
+      <version>${scala.compat.version}</version>
+    </dependency>
 
     <!--test dependencies-->
     <dependency>
@@ -79,9 +85,9 @@
       <scope>test</scope>
     </dependency>
     <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <version>${junit.version}</version>
+      <groupId>org.scalatestplus</groupId>
+      <artifactId>junit-4-13_2.12</artifactId>
+      <version>${scala.test.plus.version}</version>
       <scope>test</scope>
     </dependency>
   </dependencies>
diff --git a/samples/client/petstore/scala-akka/project/build.properties b/samples/client/petstore/scala-akka/project/build.properties
new file mode 100644
index 000000000000..dc07aed85e00
--- /dev/null
+++ b/samples/client/petstore/scala-akka/project/build.properties
@@ -0,0 +1 @@
+sbt.version=1.3.10
\ No newline at end of file
diff --git a/samples/client/petstore/scala-akka/src/main/scala/org/openapitools/client/core/ApiInvoker.scala b/samples/client/petstore/scala-akka/src/main/scala/org/openapitools/client/core/ApiInvoker.scala
index d3ff4cadb8ec..fe3910967139 100644
--- a/samples/client/petstore/scala-akka/src/main/scala/org/openapitools/client/core/ApiInvoker.scala
+++ b/samples/client/petstore/scala-akka/src/main/scala/org/openapitools/client/core/ApiInvoker.scala
@@ -28,6 +28,7 @@ import de.heikoseeberger.akkahttpjson4s.Json4sSupport
 import org.json4s._
 import org.json4s.jackson.JsonMethods._
 import org.json4s.jackson.Serialization
+import scala.collection.compat._
 
 import scala.collection.immutable
 import scala.concurrent.{ ExecutionContext, ExecutionContextExecutor, Future }
@@ -96,7 +97,7 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
 
   private val http = Http()
 
-  val CompressionFilter: HttpMessage ⇒ Boolean = (msg: HttpMessage) =>
+  val CompressionFilter: HttpMessage => Boolean = (msg: HttpMessage) =>
     Seq(
       { _: HttpMessage => settings.compressionEnabled },
       Encoder.DefaultFilter,
@@ -125,7 +126,7 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
   private def headers(headers: Map[String, Any]): immutable.Seq[HttpHeader] =
     headers.asFormattedParams
       .map { case (name, value) => RawHeader(name, value.toString) }
-      .to[immutable.Seq]
+      .to(immutable.Seq)
 
 
   private def bodyPart(name: String, value: Any): BodyPart = {
@@ -157,9 +158,9 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
           case MediaTypes.`multipart/form-data` =>
             Multipart.FormData(Source(params.toList.map { case (name, value) => bodyPart(name, value) }))
           case MediaTypes.`application/x-www-form-urlencoded` =>
-            FormData(params.mapValues(_.toString))
+            FormData(params.view.mapValues(_.toString).toMap)
           case _: MediaType => // Default : application/x-www-form-urlencoded.
-            FormData(params.mapValues(_.toString))
+            FormData(params.view.mapValues(_.toString).toMap)
         }
       )
   }
@@ -197,7 +198,9 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
         params + (keyName -> key.value)
       case (params, _) => params
     }.asFormattedParams
+      .view
       .mapValues(_.toString)
+      .toMap
       .foldRight[Query](Uri.Query.Empty) {
       case ((name, value), acc) => acc.+:(name, value)
     }
@@ -206,7 +209,9 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
   def makeUri(r: ApiRequest[_]): Uri = {
     val opPath = r.operationPath.replaceAll("\\{format\\}", "json")
     val opPathWithParams = r.pathParams.asFormattedParams
+      .view
       .mapValues(_.toString)
+      .toMap
       .foldLeft(opPath) {
         case (path, (name, value)) => path.replaceAll(s"\\{$name\\}", value)
       }
@@ -223,13 +228,13 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
     http
       .singleRequest(request)
       .map { response =>
-        val decoder: Coder with StreamDecoder = response.encoding match {
-          case HttpEncodings.gzip ⇒
-            Gzip
-          case HttpEncodings.deflate ⇒
-            Deflate
-          case HttpEncodings.identity ⇒
-            NoCoding
+        val decoder: Decoder with Decoder = response.encoding match {
+          case HttpEncodings.gzip =>
+            Coders.Gzip
+          case HttpEncodings.deflate =>
+            Coders.Deflate
+          case HttpEncodings.identity =>
+            Coders.NoCoding
           case HttpEncoding(encoding) =>
             throw new IllegalArgumentException(s"Unsupported encoding: $encoding")
         }
@@ -257,13 +262,13 @@ class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends CustomC
     request
       .responseForCode(response.status.intValue) match {
       case Some((Manifest.Unit, state: ResponseState)) =>
-        Future(responseForState(state, Unit).asInstanceOf[ApiResponse[T]])
+        Future(responseForState(state, ()).asInstanceOf[ApiResponse[T]])
       case Some((manifest, state: ResponseState)) if manifest == mf =>
         implicit val m: Unmarshaller[HttpEntity, T] = unmarshaller[T](mf, serialization, formats)
         Unmarshal(response.entity)
           .to[T]
           .recoverWith {
-            case e ⇒ throw ApiError(response.status.intValue, s"Unable to unmarshall content to [$manifest]", Some(response.entity.toString), e)
+            case e => throw ApiError(response.status.intValue, s"Unable to unmarshall content to [$manifest]", Some(response.entity.toString), e)
           }
           .map(value => responseForState(state, value))
       case None | Some(_) =>
diff --git a/samples/client/petstore/scala-akka/src/main/scala/org/openapitools/client/core/ApiSettings.scala b/samples/client/petstore/scala-akka/src/main/scala/org/openapitools/client/core/ApiSettings.scala
index 2553aeb3c875..2c02c47c7bac 100644
--- a/samples/client/petstore/scala-akka/src/main/scala/org/openapitools/client/core/ApiSettings.scala
+++ b/samples/client/petstore/scala-akka/src/main/scala/org/openapitools/client/core/ApiSettings.scala
@@ -13,12 +13,12 @@ package org.openapitools.client.core
 
 import java.util.concurrent.TimeUnit
 
-import akka.actor.{ ExtendedActorSystem, Extension, ExtensionKey }
+import akka.actor.{ActorSystem, ExtendedActorSystem, Extension, ExtensionId, ExtensionIdProvider}
 import akka.http.scaladsl.model.StatusCodes.CustomStatusCode
 import akka.http.scaladsl.model.headers.RawHeader
 import com.typesafe.config.Config
 
-import scala.collection.JavaConverters._
+import scala.jdk.CollectionConverters._
 import scala.concurrent.duration.FiniteDuration
 
 class ApiSettings(config: Config) extends Extension {
@@ -42,4 +42,13 @@ class ApiSettings(config: Config) extends Extension {
   }
 }
 
-object ApiSettings extends ExtensionKey[ApiSettings]
+object ApiSettings extends ExtensionId[ApiSettings] with ExtensionIdProvider {
+
+  override def lookup = ApiSettings
+
+  override def createExtension(system: ExtendedActorSystem): ApiSettings =
+    new ApiSettings(system)
+
+  // needed to get the type right when used from Java
+  override def get(system: ActorSystem): ApiSettings = super.get(system)
+}
diff --git a/samples/client/petstore/scala-akka/src/test/scala/PetApiTest.scala b/samples/client/petstore/scala-akka/src/test/scala/PetApiTest.scala
index e6229fb05f3a..48c8d4c644fd 100644
--- a/samples/client/petstore/scala-akka/src/test/scala/PetApiTest.scala
+++ b/samples/client/petstore/scala-akka/src/test/scala/PetApiTest.scala
@@ -5,18 +5,19 @@ import org.openapitools.client.api._
 import org.openapitools.client.core.{ApiInvoker, ApiKeyValue}
 import org.openapitools.client.model._
 import org.scalatest.Inspectors._
-import org.scalatest._
-import org.scalatest.junit.JUnitRunner
+import org.scalatest.flatspec.AsyncFlatSpec
+import org.scalatest.matchers.should.Matchers
+import org.scalatestplus.junit.JUnitRunner
 
 @RunWith(classOf[JUnitRunner])
 class PetApiTest extends AsyncFlatSpec with Matchers {
 
-  private implicit val system: ActorSystem = ActorSystem()
+  implicit private val system: ActorSystem = ActorSystem()
 
   behavior of "PetApi"
-  val api: PetApi = PetApi()
-  val invoker: ApiInvoker = ApiInvoker(EnumsSerializers.all)
-  private implicit val apiKey: ApiKeyValue = ApiKeyValue("special-key")
+  val api: PetApi                          = PetApi()
+  val invoker: ApiInvoker                  = ApiInvoker(EnumsSerializers.all)
+  implicit private val apiKey: ApiKeyValue = ApiKeyValue("special-key")
 
   it should "add and fetch a pet" in {
     val petId = 1000
@@ -34,7 +35,7 @@ class PetApiTest extends AsyncFlatSpec with Matchers {
 
     for {
       addResponse <- invoker.execute(addPetRequest)
-      response <- invoker.execute(getPetRequest)
+      response    <- invoker.execute(getPetRequest)
     } yield {
       addResponse.code should be(200)
 
@@ -54,7 +55,7 @@ class PetApiTest extends AsyncFlatSpec with Matchers {
   }
 
   it should "update a pet" in {
-    val petId = (Math.random()*1000000000).toLong
+    val petId = (Math.random() * 1000000000).toLong
     val createdPet = Pet(
       Some(petId),
       Some(Category(Some(1), Some("sold"))),
@@ -64,12 +65,12 @@ class PetApiTest extends AsyncFlatSpec with Matchers {
       Some(PetEnums.Status.Available)
     )
 
-     for {
-      createdPet <- invoker.execute(api.addPet(createdPet))
+    for {
+      createdPet                 <- invoker.execute(api.addPet(createdPet))
       pet: core.ApiResponse[Pet] <- invoker.execute(api.getPetById(createdPet.content.id.get))
       updatedPet = pet.content.copy(status = Some(PetEnums.Status.Sold), name = "developer")
       updatedPetResponse: core.ApiResponse[Pet] <- invoker.execute(api.updatePet(updatedPet))
-      updatedRequested: core.ApiResponse[Pet] <- invoker.execute(api.getPetById(createdPet.content.id.get))
+      updatedRequested: core.ApiResponse[Pet]   <- invoker.execute(api.getPetById(createdPet.content.id.get))
     } yield {
       pet.content.name should be("programmer")
       pet.content.status should be(Some(PetEnums.Status.Available))
@@ -120,4 +121,3 @@ class PetApiTest extends AsyncFlatSpec with Matchers {
   }
   */
 }
-

From a88313c40ce5fcc3264119670756ce5813bb24ac Mon Sep 17 00:00:00 2001
From: johnthagen <johnthagen@users.noreply.github.com>
Date: Fri, 30 Apr 2021 14:59:33 -0400
Subject: [PATCH 05/18] [Python] Avoid DeprecationWarning in inspect.getargspec
 on Python 3 (#9271)

* Avoid DeprecationWarning in inspect.getargspec on Python 3

* Regenerate samples
---
 .../src/main/resources/python-legacy/model.mustache        | 7 +++++--
 .../petstore_api/models/additional_properties_any_type.py  | 7 +++++--
 .../petstore_api/models/additional_properties_array.py     | 7 +++++--
 .../petstore_api/models/additional_properties_boolean.py   | 7 +++++--
 .../petstore_api/models/additional_properties_class.py     | 7 +++++--
 .../petstore_api/models/additional_properties_integer.py   | 7 +++++--
 .../petstore_api/models/additional_properties_number.py    | 7 +++++--
 .../petstore_api/models/additional_properties_object.py    | 7 +++++--
 .../petstore_api/models/additional_properties_string.py    | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/animal.py  | 7 +++++--
 .../python-asyncio/petstore_api/models/api_response.py     | 7 +++++--
 .../petstore_api/models/array_of_array_of_number_only.py   | 7 +++++--
 .../petstore_api/models/array_of_number_only.py            | 7 +++++--
 .../python-asyncio/petstore_api/models/array_test.py       | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/big_cat.py | 7 +++++--
 .../python-asyncio/petstore_api/models/big_cat_all_of.py   | 7 +++++--
 .../python-asyncio/petstore_api/models/capitalization.py   | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/cat.py     | 7 +++++--
 .../python-asyncio/petstore_api/models/cat_all_of.py       | 7 +++++--
 .../python-asyncio/petstore_api/models/category.py         | 7 +++++--
 .../python-asyncio/petstore_api/models/class_model.py      | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/client.py  | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/dog.py     | 7 +++++--
 .../python-asyncio/petstore_api/models/dog_all_of.py       | 7 +++++--
 .../python-asyncio/petstore_api/models/enum_arrays.py      | 7 +++++--
 .../python-asyncio/petstore_api/models/enum_class.py       | 7 +++++--
 .../python-asyncio/petstore_api/models/enum_test.py        | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/file.py    | 7 +++++--
 .../petstore_api/models/file_schema_test_class.py          | 7 +++++--
 .../python-asyncio/petstore_api/models/format_test.py      | 7 +++++--
 .../petstore_api/models/has_only_read_only.py              | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/list.py    | 7 +++++--
 .../python-asyncio/petstore_api/models/map_test.py         | 7 +++++--
 .../mixed_properties_and_additional_properties_class.py    | 7 +++++--
 .../petstore_api/models/model200_response.py               | 7 +++++--
 .../python-asyncio/petstore_api/models/model_return.py     | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/name.py    | 7 +++++--
 .../python-asyncio/petstore_api/models/number_only.py      | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/order.py   | 7 +++++--
 .../python-asyncio/petstore_api/models/outer_composite.py  | 7 +++++--
 .../python-asyncio/petstore_api/models/outer_enum.py       | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/pet.py     | 7 +++++--
 .../python-asyncio/petstore_api/models/read_only_first.py  | 7 +++++--
 .../petstore_api/models/special_model_name.py              | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/tag.py     | 7 +++++--
 .../petstore_api/models/type_holder_default.py             | 7 +++++--
 .../petstore_api/models/type_holder_example.py             | 7 +++++--
 .../petstore/python-asyncio/petstore_api/models/user.py    | 7 +++++--
 .../python-asyncio/petstore_api/models/xml_item.py         | 7 +++++--
 .../petstore_api/models/additional_properties_any_type.py  | 7 +++++--
 .../petstore_api/models/additional_properties_array.py     | 7 +++++--
 .../petstore_api/models/additional_properties_boolean.py   | 7 +++++--
 .../petstore_api/models/additional_properties_class.py     | 7 +++++--
 .../petstore_api/models/additional_properties_integer.py   | 7 +++++--
 .../petstore_api/models/additional_properties_number.py    | 7 +++++--
 .../petstore_api/models/additional_properties_object.py    | 7 +++++--
 .../petstore_api/models/additional_properties_string.py    | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/animal.py   | 7 +++++--
 .../python-legacy/petstore_api/models/api_response.py      | 7 +++++--
 .../petstore_api/models/array_of_array_of_number_only.py   | 7 +++++--
 .../petstore_api/models/array_of_number_only.py            | 7 +++++--
 .../python-legacy/petstore_api/models/array_test.py        | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/big_cat.py  | 7 +++++--
 .../python-legacy/petstore_api/models/big_cat_all_of.py    | 7 +++++--
 .../python-legacy/petstore_api/models/capitalization.py    | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/cat.py      | 7 +++++--
 .../python-legacy/petstore_api/models/cat_all_of.py        | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/category.py | 7 +++++--
 .../python-legacy/petstore_api/models/class_model.py       | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/client.py   | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/dog.py      | 7 +++++--
 .../python-legacy/petstore_api/models/dog_all_of.py        | 7 +++++--
 .../python-legacy/petstore_api/models/enum_arrays.py       | 7 +++++--
 .../python-legacy/petstore_api/models/enum_class.py        | 7 +++++--
 .../python-legacy/petstore_api/models/enum_test.py         | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/file.py     | 7 +++++--
 .../petstore_api/models/file_schema_test_class.py          | 7 +++++--
 .../python-legacy/petstore_api/models/format_test.py       | 7 +++++--
 .../petstore_api/models/has_only_read_only.py              | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/list.py     | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/map_test.py | 7 +++++--
 .../mixed_properties_and_additional_properties_class.py    | 7 +++++--
 .../python-legacy/petstore_api/models/model200_response.py | 7 +++++--
 .../python-legacy/petstore_api/models/model_return.py      | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/name.py     | 7 +++++--
 .../python-legacy/petstore_api/models/number_only.py       | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/order.py    | 7 +++++--
 .../python-legacy/petstore_api/models/outer_composite.py   | 7 +++++--
 .../python-legacy/petstore_api/models/outer_enum.py        | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/pet.py      | 7 +++++--
 .../python-legacy/petstore_api/models/read_only_first.py   | 7 +++++--
 .../petstore_api/models/special_model_name.py              | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/tag.py      | 7 +++++--
 .../petstore_api/models/type_holder_default.py             | 7 +++++--
 .../petstore_api/models/type_holder_example.py             | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/user.py     | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/xml_item.py | 7 +++++--
 .../petstore_api/models/additional_properties_any_type.py  | 7 +++++--
 .../petstore_api/models/additional_properties_array.py     | 7 +++++--
 .../petstore_api/models/additional_properties_boolean.py   | 7 +++++--
 .../petstore_api/models/additional_properties_class.py     | 7 +++++--
 .../petstore_api/models/additional_properties_integer.py   | 7 +++++--
 .../petstore_api/models/additional_properties_number.py    | 7 +++++--
 .../petstore_api/models/additional_properties_object.py    | 7 +++++--
 .../petstore_api/models/additional_properties_string.py    | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/animal.py  | 7 +++++--
 .../python-tornado/petstore_api/models/api_response.py     | 7 +++++--
 .../petstore_api/models/array_of_array_of_number_only.py   | 7 +++++--
 .../petstore_api/models/array_of_number_only.py            | 7 +++++--
 .../python-tornado/petstore_api/models/array_test.py       | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/big_cat.py | 7 +++++--
 .../python-tornado/petstore_api/models/big_cat_all_of.py   | 7 +++++--
 .../python-tornado/petstore_api/models/capitalization.py   | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/cat.py     | 7 +++++--
 .../python-tornado/petstore_api/models/cat_all_of.py       | 7 +++++--
 .../python-tornado/petstore_api/models/category.py         | 7 +++++--
 .../python-tornado/petstore_api/models/class_model.py      | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/client.py  | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/dog.py     | 7 +++++--
 .../python-tornado/petstore_api/models/dog_all_of.py       | 7 +++++--
 .../python-tornado/petstore_api/models/enum_arrays.py      | 7 +++++--
 .../python-tornado/petstore_api/models/enum_class.py       | 7 +++++--
 .../python-tornado/petstore_api/models/enum_test.py        | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/file.py    | 7 +++++--
 .../petstore_api/models/file_schema_test_class.py          | 7 +++++--
 .../python-tornado/petstore_api/models/format_test.py      | 7 +++++--
 .../petstore_api/models/has_only_read_only.py              | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/list.py    | 7 +++++--
 .../python-tornado/petstore_api/models/map_test.py         | 7 +++++--
 .../mixed_properties_and_additional_properties_class.py    | 7 +++++--
 .../petstore_api/models/model200_response.py               | 7 +++++--
 .../python-tornado/petstore_api/models/model_return.py     | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/name.py    | 7 +++++--
 .../python-tornado/petstore_api/models/number_only.py      | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/order.py   | 7 +++++--
 .../python-tornado/petstore_api/models/outer_composite.py  | 7 +++++--
 .../python-tornado/petstore_api/models/outer_enum.py       | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/pet.py     | 7 +++++--
 .../python-tornado/petstore_api/models/read_only_first.py  | 7 +++++--
 .../petstore_api/models/special_model_name.py              | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/tag.py     | 7 +++++--
 .../petstore_api/models/type_holder_default.py             | 7 +++++--
 .../petstore_api/models/type_holder_example.py             | 7 +++++--
 .../petstore/python-tornado/petstore_api/models/user.py    | 7 +++++--
 .../python-tornado/petstore_api/models/xml_item.py         | 7 +++++--
 .../petstore_api/models/additional_properties_class.py     | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/animal.py   | 7 +++++--
 .../python-legacy/petstore_api/models/api_response.py      | 7 +++++--
 .../petstore_api/models/array_of_array_of_number_only.py   | 7 +++++--
 .../petstore_api/models/array_of_number_only.py            | 7 +++++--
 .../python-legacy/petstore_api/models/array_test.py        | 7 +++++--
 .../python-legacy/petstore_api/models/capitalization.py    | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/cat.py      | 7 +++++--
 .../python-legacy/petstore_api/models/cat_all_of.py        | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/category.py | 7 +++++--
 .../python-legacy/petstore_api/models/class_model.py       | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/client.py   | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/dog.py      | 7 +++++--
 .../python-legacy/petstore_api/models/dog_all_of.py        | 7 +++++--
 .../python-legacy/petstore_api/models/enum_arrays.py       | 7 +++++--
 .../python-legacy/petstore_api/models/enum_class.py        | 7 +++++--
 .../python-legacy/petstore_api/models/enum_test.py         | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/file.py     | 7 +++++--
 .../petstore_api/models/file_schema_test_class.py          | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/foo.py      | 7 +++++--
 .../python-legacy/petstore_api/models/format_test.py       | 7 +++++--
 .../petstore_api/models/has_only_read_only.py              | 7 +++++--
 .../petstore_api/models/health_check_result.py             | 7 +++++--
 .../petstore_api/models/inline_response_default.py         | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/list.py     | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/map_test.py | 7 +++++--
 .../mixed_properties_and_additional_properties_class.py    | 7 +++++--
 .../python-legacy/petstore_api/models/model200_response.py | 7 +++++--
 .../python-legacy/petstore_api/models/model_return.py      | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/name.py     | 7 +++++--
 .../python-legacy/petstore_api/models/nullable_class.py    | 7 +++++--
 .../python-legacy/petstore_api/models/number_only.py       | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/order.py    | 7 +++++--
 .../python-legacy/petstore_api/models/outer_composite.py   | 7 +++++--
 .../python-legacy/petstore_api/models/outer_enum.py        | 7 +++++--
 .../petstore_api/models/outer_enum_default_value.py        | 7 +++++--
 .../petstore_api/models/outer_enum_integer.py              | 7 +++++--
 .../models/outer_enum_integer_default_value.py             | 7 +++++--
 .../petstore_api/models/outer_object_with_enum_property.py | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/pet.py      | 7 +++++--
 .../python-legacy/petstore_api/models/read_only_first.py   | 7 +++++--
 .../petstore_api/models/special_model_name.py              | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/tag.py      | 7 +++++--
 .../petstore/python-legacy/petstore_api/models/user.py     | 7 +++++--
 189 files changed, 945 insertions(+), 378 deletions(-)

diff --git a/modules/openapi-generator/src/main/resources/python-legacy/model.mustache b/modules/openapi-generator/src/main/resources/python-legacy/model.mustache
index 5b4048915eb8..236b8f8c3a2e 100644
--- a/modules/openapi-generator/src/main/resources/python-legacy/model.mustache
+++ b/modules/openapi-generator/src/main/resources/python-legacy/model.mustache
@@ -2,7 +2,10 @@
 
 {{>partial_header}}
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -203,7 +206,7 @@ class {{classname}}(object):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_any_type.py b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_any_type.py
index 30e6e9b81766..01457faa3a33 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_any_type.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_any_type.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_array.py b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_array.py
index 2f939711e0af..c7283e161360 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_array.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_array.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_boolean.py b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_boolean.py
index 32b58c24ffa8..3a8ec8f66aac 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_boolean.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_boolean.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_class.py b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_class.py
index dff689699744..52c475c4460c 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_class.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -339,7 +342,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_integer.py b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_integer.py
index bba82b9c8cf9..d9ee889d7a33 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_integer.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_integer.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_number.py b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_number.py
index 9adeedb7e792..756fc037970f 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_number.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_number.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_object.py b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_object.py
index 85f94ac205df..bfbe2db1bef9 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_object.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_object.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_string.py b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_string.py
index ee8d6383348c..7c33a16fe8fc 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_string.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/additional_properties_string.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/animal.py b/samples/client/petstore/python-asyncio/petstore_api/models/animal.py
index a791a5173ba1..eee29f37f881 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/animal.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/animal.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -118,7 +121,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/api_response.py b/samples/client/petstore/python-asyncio/petstore_api/models/api_response.py
index ab5e7999dd2f..bddac1eb10a3 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/api_response.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/api_response.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/array_of_array_of_number_only.py b/samples/client/petstore/python-asyncio/petstore_api/models/array_of_array_of_number_only.py
index c9b65c7e5315..2975adc20e31 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/array_of_array_of_number_only.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/array_of_array_of_number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/array_of_number_only.py b/samples/client/petstore/python-asyncio/petstore_api/models/array_of_number_only.py
index 870286e0fc08..2a3400e76660 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/array_of_number_only.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/array_of_number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/array_test.py b/samples/client/petstore/python-asyncio/petstore_api/models/array_test.py
index 04d2cb6ec602..11394dcb7bc1 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/array_test.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/array_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/big_cat.py b/samples/client/petstore/python-asyncio/petstore_api/models/big_cat.py
index 7136aa867207..9a108ce3717e 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/big_cat.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/big_cat.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -85,7 +88,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/big_cat_all_of.py b/samples/client/petstore/python-asyncio/petstore_api/models/big_cat_all_of.py
index 127e7c6da31a..6d6c9aeb5c0c 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/big_cat_all_of.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/big_cat_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -85,7 +88,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/capitalization.py b/samples/client/petstore/python-asyncio/petstore_api/models/capitalization.py
index 064dc2eb2ff5..cb8b0d985842 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/capitalization.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/capitalization.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -211,7 +214,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/cat.py b/samples/client/petstore/python-asyncio/petstore_api/models/cat.py
index 3b6e6aa4c2e8..0d9a0b20bf1a 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/cat.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/cat.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/cat_all_of.py b/samples/client/petstore/python-asyncio/petstore_api/models/cat_all_of.py
index 7755fd65b0c3..0633bbf58d0d 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/cat_all_of.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/cat_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/category.py b/samples/client/petstore/python-asyncio/petstore_api/models/category.py
index c3dd5a4b9a17..ef52dcbf8c91 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/category.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/category.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -106,7 +109,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/class_model.py b/samples/client/petstore/python-asyncio/petstore_api/models/class_model.py
index cd9439763d20..84c0de65b472 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/class_model.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/class_model.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/client.py b/samples/client/petstore/python-asyncio/petstore_api/models/client.py
index f896b35240c7..8d7c83ecfe6b 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/client.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/client.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/dog.py b/samples/client/petstore/python-asyncio/petstore_api/models/dog.py
index 39514284d5f2..61acd35cdfe2 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/dog.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/dog.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/dog_all_of.py b/samples/client/petstore/python-asyncio/petstore_api/models/dog_all_of.py
index 207103a48745..3a052c3258ae 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/dog_all_of.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/dog_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/enum_arrays.py b/samples/client/petstore/python-asyncio/petstore_api/models/enum_arrays.py
index b87cd37456e1..eb4f3ea4ca32 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/enum_arrays.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/enum_arrays.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -119,7 +122,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/enum_class.py b/samples/client/petstore/python-asyncio/petstore_api/models/enum_class.py
index 4b11877863ac..79aac3570cb9 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/enum_class.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/enum_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/enum_test.py b/samples/client/petstore/python-asyncio/petstore_api/models/enum_test.py
index d1778410dee2..1f3d7cb29b89 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/enum_test.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/enum_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -208,7 +211,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/file.py b/samples/client/petstore/python-asyncio/petstore_api/models/file.py
index e40cd04b0149..2c1cccac0e11 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/file.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/file.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -81,7 +84,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/file_schema_test_class.py b/samples/client/petstore/python-asyncio/petstore_api/models/file_schema_test_class.py
index d266755d260a..c5a23842d4f6 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/file_schema_test_class.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/file_schema_test_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/format_test.py b/samples/client/petstore/python-asyncio/petstore_api/models/format_test.py
index c193f9313e96..452582251a59 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/format_test.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/format_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -463,7 +466,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/has_only_read_only.py b/samples/client/petstore/python-asyncio/petstore_api/models/has_only_read_only.py
index dac8cfaff937..7175c2acc721 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/has_only_read_only.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/has_only_read_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/list.py b/samples/client/petstore/python-asyncio/petstore_api/models/list.py
index b44257224741..6e1dea4e33b5 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/list.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/list.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/map_test.py b/samples/client/petstore/python-asyncio/petstore_api/models/map_test.py
index 406f35db7500..21bd2ccda980 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/map_test.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/map_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -165,7 +168,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/mixed_properties_and_additional_properties_class.py b/samples/client/petstore/python-asyncio/petstore_api/models/mixed_properties_and_additional_properties_class.py
index 14428a6536a8..9e727b07d5c7 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/mixed_properties_and_additional_properties_class.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/mixed_properties_and_additional_properties_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/model200_response.py b/samples/client/petstore/python-asyncio/petstore_api/models/model200_response.py
index 5c90147467b5..db587fd24e2f 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/model200_response.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/model200_response.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/model_return.py b/samples/client/petstore/python-asyncio/petstore_api/models/model_return.py
index 88174ef23083..5354fd56e2ce 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/model_return.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/model_return.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/name.py b/samples/client/petstore/python-asyncio/petstore_api/models/name.py
index 528988ebd437..0191a3a934ae 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/name.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/name.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -158,7 +161,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/number_only.py b/samples/client/petstore/python-asyncio/petstore_api/models/number_only.py
index ebbcc8996d01..59a252e0bb66 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/number_only.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/order.py b/samples/client/petstore/python-asyncio/petstore_api/models/order.py
index 6513d48a3a5e..a267324d0d19 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/order.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/order.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -217,7 +220,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/outer_composite.py b/samples/client/petstore/python-asyncio/petstore_api/models/outer_composite.py
index 44124e13c09b..e26160ab4302 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/outer_composite.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/outer_composite.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/outer_enum.py b/samples/client/petstore/python-asyncio/petstore_api/models/outer_enum.py
index 77624ba15408..27cdfd1fb791 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/outer_enum.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/outer_enum.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/pet.py b/samples/client/petstore/python-asyncio/petstore_api/models/pet.py
index e71589429ca0..22bb4a585e47 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/pet.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/pet.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -219,7 +222,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/read_only_first.py b/samples/client/petstore/python-asyncio/petstore_api/models/read_only_first.py
index 3a320fe64f06..c2888eba7500 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/read_only_first.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/read_only_first.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/special_model_name.py b/samples/client/petstore/python-asyncio/petstore_api/models/special_model_name.py
index 7669a508789f..4c848e1887c0 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/special_model_name.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/special_model_name.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/tag.py b/samples/client/petstore/python-asyncio/petstore_api/models/tag.py
index dbac885ad8e9..a3e6789078d8 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/tag.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/tag.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/type_holder_default.py b/samples/client/petstore/python-asyncio/petstore_api/models/type_holder_default.py
index c890f5531927..582b4c8d6dc2 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/type_holder_default.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/type_holder_default.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -188,7 +191,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/type_holder_example.py b/samples/client/petstore/python-asyncio/petstore_api/models/type_holder_example.py
index d52425d442ea..268595ed8681 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/type_holder_example.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/type_holder_example.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -215,7 +218,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/user.py b/samples/client/petstore/python-asyncio/petstore_api/models/user.py
index b70d84a6b40e..7ae2898f6c5a 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/user.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/user.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -263,7 +266,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-asyncio/petstore_api/models/xml_item.py b/samples/client/petstore/python-asyncio/petstore_api/models/xml_item.py
index d63ab77acfde..5e6fecdd71c8 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/models/xml_item.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/models/xml_item.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -807,7 +810,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_any_type.py b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_any_type.py
index 30e6e9b81766..01457faa3a33 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_any_type.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_any_type.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_array.py b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_array.py
index 2f939711e0af..c7283e161360 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_array.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_array.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_boolean.py b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_boolean.py
index 32b58c24ffa8..3a8ec8f66aac 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_boolean.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_boolean.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_class.py b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_class.py
index dff689699744..52c475c4460c 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_class.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -339,7 +342,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_integer.py b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_integer.py
index bba82b9c8cf9..d9ee889d7a33 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_integer.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_integer.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_number.py b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_number.py
index 9adeedb7e792..756fc037970f 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_number.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_number.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_object.py b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_object.py
index 85f94ac205df..bfbe2db1bef9 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_object.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_object.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_string.py b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_string.py
index ee8d6383348c..7c33a16fe8fc 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_string.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/additional_properties_string.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/animal.py b/samples/client/petstore/python-legacy/petstore_api/models/animal.py
index a791a5173ba1..eee29f37f881 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/animal.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/animal.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -118,7 +121,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/api_response.py b/samples/client/petstore/python-legacy/petstore_api/models/api_response.py
index ab5e7999dd2f..bddac1eb10a3 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/api_response.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/api_response.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/array_of_array_of_number_only.py b/samples/client/petstore/python-legacy/petstore_api/models/array_of_array_of_number_only.py
index c9b65c7e5315..2975adc20e31 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/array_of_array_of_number_only.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/array_of_array_of_number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/array_of_number_only.py b/samples/client/petstore/python-legacy/petstore_api/models/array_of_number_only.py
index 870286e0fc08..2a3400e76660 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/array_of_number_only.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/array_of_number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/array_test.py b/samples/client/petstore/python-legacy/petstore_api/models/array_test.py
index 04d2cb6ec602..11394dcb7bc1 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/array_test.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/array_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/big_cat.py b/samples/client/petstore/python-legacy/petstore_api/models/big_cat.py
index 7136aa867207..9a108ce3717e 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/big_cat.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/big_cat.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -85,7 +88,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/big_cat_all_of.py b/samples/client/petstore/python-legacy/petstore_api/models/big_cat_all_of.py
index 127e7c6da31a..6d6c9aeb5c0c 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/big_cat_all_of.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/big_cat_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -85,7 +88,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/capitalization.py b/samples/client/petstore/python-legacy/petstore_api/models/capitalization.py
index 064dc2eb2ff5..cb8b0d985842 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/capitalization.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/capitalization.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -211,7 +214,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/cat.py b/samples/client/petstore/python-legacy/petstore_api/models/cat.py
index 3b6e6aa4c2e8..0d9a0b20bf1a 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/cat.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/cat.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/cat_all_of.py b/samples/client/petstore/python-legacy/petstore_api/models/cat_all_of.py
index 7755fd65b0c3..0633bbf58d0d 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/cat_all_of.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/cat_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/category.py b/samples/client/petstore/python-legacy/petstore_api/models/category.py
index c3dd5a4b9a17..ef52dcbf8c91 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/category.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/category.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -106,7 +109,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/class_model.py b/samples/client/petstore/python-legacy/petstore_api/models/class_model.py
index cd9439763d20..84c0de65b472 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/class_model.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/class_model.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/client.py b/samples/client/petstore/python-legacy/petstore_api/models/client.py
index f896b35240c7..8d7c83ecfe6b 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/client.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/client.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/dog.py b/samples/client/petstore/python-legacy/petstore_api/models/dog.py
index 39514284d5f2..61acd35cdfe2 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/dog.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/dog.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/dog_all_of.py b/samples/client/petstore/python-legacy/petstore_api/models/dog_all_of.py
index 207103a48745..3a052c3258ae 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/dog_all_of.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/dog_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/enum_arrays.py b/samples/client/petstore/python-legacy/petstore_api/models/enum_arrays.py
index b87cd37456e1..eb4f3ea4ca32 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/enum_arrays.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/enum_arrays.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -119,7 +122,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/enum_class.py b/samples/client/petstore/python-legacy/petstore_api/models/enum_class.py
index 4b11877863ac..79aac3570cb9 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/enum_class.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/enum_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/enum_test.py b/samples/client/petstore/python-legacy/petstore_api/models/enum_test.py
index d1778410dee2..1f3d7cb29b89 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/enum_test.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/enum_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -208,7 +211,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/file.py b/samples/client/petstore/python-legacy/petstore_api/models/file.py
index e40cd04b0149..2c1cccac0e11 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/file.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/file.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -81,7 +84,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/file_schema_test_class.py b/samples/client/petstore/python-legacy/petstore_api/models/file_schema_test_class.py
index d266755d260a..c5a23842d4f6 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/file_schema_test_class.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/file_schema_test_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/format_test.py b/samples/client/petstore/python-legacy/petstore_api/models/format_test.py
index c193f9313e96..452582251a59 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/format_test.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/format_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -463,7 +466,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/has_only_read_only.py b/samples/client/petstore/python-legacy/petstore_api/models/has_only_read_only.py
index dac8cfaff937..7175c2acc721 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/has_only_read_only.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/has_only_read_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/list.py b/samples/client/petstore/python-legacy/petstore_api/models/list.py
index b44257224741..6e1dea4e33b5 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/list.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/list.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/map_test.py b/samples/client/petstore/python-legacy/petstore_api/models/map_test.py
index 406f35db7500..21bd2ccda980 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/map_test.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/map_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -165,7 +168,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/mixed_properties_and_additional_properties_class.py b/samples/client/petstore/python-legacy/petstore_api/models/mixed_properties_and_additional_properties_class.py
index 14428a6536a8..9e727b07d5c7 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/mixed_properties_and_additional_properties_class.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/mixed_properties_and_additional_properties_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/model200_response.py b/samples/client/petstore/python-legacy/petstore_api/models/model200_response.py
index 5c90147467b5..db587fd24e2f 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/model200_response.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/model200_response.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/model_return.py b/samples/client/petstore/python-legacy/petstore_api/models/model_return.py
index 88174ef23083..5354fd56e2ce 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/model_return.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/model_return.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/name.py b/samples/client/petstore/python-legacy/petstore_api/models/name.py
index 528988ebd437..0191a3a934ae 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/name.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/name.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -158,7 +161,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/number_only.py b/samples/client/petstore/python-legacy/petstore_api/models/number_only.py
index ebbcc8996d01..59a252e0bb66 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/number_only.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/order.py b/samples/client/petstore/python-legacy/petstore_api/models/order.py
index 6513d48a3a5e..a267324d0d19 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/order.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/order.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -217,7 +220,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/outer_composite.py b/samples/client/petstore/python-legacy/petstore_api/models/outer_composite.py
index 44124e13c09b..e26160ab4302 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/outer_composite.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/outer_composite.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/outer_enum.py b/samples/client/petstore/python-legacy/petstore_api/models/outer_enum.py
index 77624ba15408..27cdfd1fb791 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/outer_enum.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/outer_enum.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/pet.py b/samples/client/petstore/python-legacy/petstore_api/models/pet.py
index e71589429ca0..22bb4a585e47 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/pet.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/pet.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -219,7 +222,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/read_only_first.py b/samples/client/petstore/python-legacy/petstore_api/models/read_only_first.py
index 3a320fe64f06..c2888eba7500 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/read_only_first.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/read_only_first.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/special_model_name.py b/samples/client/petstore/python-legacy/petstore_api/models/special_model_name.py
index 7669a508789f..4c848e1887c0 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/special_model_name.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/special_model_name.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/tag.py b/samples/client/petstore/python-legacy/petstore_api/models/tag.py
index dbac885ad8e9..a3e6789078d8 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/tag.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/tag.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/type_holder_default.py b/samples/client/petstore/python-legacy/petstore_api/models/type_holder_default.py
index c890f5531927..582b4c8d6dc2 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/type_holder_default.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/type_holder_default.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -188,7 +191,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/type_holder_example.py b/samples/client/petstore/python-legacy/petstore_api/models/type_holder_example.py
index d52425d442ea..268595ed8681 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/type_holder_example.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/type_holder_example.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -215,7 +218,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/user.py b/samples/client/petstore/python-legacy/petstore_api/models/user.py
index b70d84a6b40e..7ae2898f6c5a 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/user.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/user.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -263,7 +266,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-legacy/petstore_api/models/xml_item.py b/samples/client/petstore/python-legacy/petstore_api/models/xml_item.py
index d63ab77acfde..5e6fecdd71c8 100644
--- a/samples/client/petstore/python-legacy/petstore_api/models/xml_item.py
+++ b/samples/client/petstore/python-legacy/petstore_api/models/xml_item.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -807,7 +810,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_any_type.py b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_any_type.py
index 30e6e9b81766..01457faa3a33 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_any_type.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_any_type.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_array.py b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_array.py
index 2f939711e0af..c7283e161360 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_array.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_array.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_boolean.py b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_boolean.py
index 32b58c24ffa8..3a8ec8f66aac 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_boolean.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_boolean.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_class.py b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_class.py
index dff689699744..52c475c4460c 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_class.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -339,7 +342,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_integer.py b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_integer.py
index bba82b9c8cf9..d9ee889d7a33 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_integer.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_integer.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_number.py b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_number.py
index 9adeedb7e792..756fc037970f 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_number.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_number.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_object.py b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_object.py
index 85f94ac205df..bfbe2db1bef9 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_object.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_object.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_string.py b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_string.py
index ee8d6383348c..7c33a16fe8fc 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_string.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/additional_properties_string.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/animal.py b/samples/client/petstore/python-tornado/petstore_api/models/animal.py
index a791a5173ba1..eee29f37f881 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/animal.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/animal.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -118,7 +121,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/api_response.py b/samples/client/petstore/python-tornado/petstore_api/models/api_response.py
index ab5e7999dd2f..bddac1eb10a3 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/api_response.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/api_response.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/array_of_array_of_number_only.py b/samples/client/petstore/python-tornado/petstore_api/models/array_of_array_of_number_only.py
index c9b65c7e5315..2975adc20e31 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/array_of_array_of_number_only.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/array_of_array_of_number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/array_of_number_only.py b/samples/client/petstore/python-tornado/petstore_api/models/array_of_number_only.py
index 870286e0fc08..2a3400e76660 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/array_of_number_only.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/array_of_number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/array_test.py b/samples/client/petstore/python-tornado/petstore_api/models/array_test.py
index 04d2cb6ec602..11394dcb7bc1 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/array_test.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/array_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/big_cat.py b/samples/client/petstore/python-tornado/petstore_api/models/big_cat.py
index 7136aa867207..9a108ce3717e 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/big_cat.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/big_cat.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -85,7 +88,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/big_cat_all_of.py b/samples/client/petstore/python-tornado/petstore_api/models/big_cat_all_of.py
index 127e7c6da31a..6d6c9aeb5c0c 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/big_cat_all_of.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/big_cat_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -85,7 +88,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/capitalization.py b/samples/client/petstore/python-tornado/petstore_api/models/capitalization.py
index 064dc2eb2ff5..cb8b0d985842 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/capitalization.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/capitalization.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -211,7 +214,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/cat.py b/samples/client/petstore/python-tornado/petstore_api/models/cat.py
index 3b6e6aa4c2e8..0d9a0b20bf1a 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/cat.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/cat.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/cat_all_of.py b/samples/client/petstore/python-tornado/petstore_api/models/cat_all_of.py
index 7755fd65b0c3..0633bbf58d0d 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/cat_all_of.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/cat_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/category.py b/samples/client/petstore/python-tornado/petstore_api/models/category.py
index c3dd5a4b9a17..ef52dcbf8c91 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/category.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/category.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -106,7 +109,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/class_model.py b/samples/client/petstore/python-tornado/petstore_api/models/class_model.py
index cd9439763d20..84c0de65b472 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/class_model.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/class_model.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/client.py b/samples/client/petstore/python-tornado/petstore_api/models/client.py
index f896b35240c7..8d7c83ecfe6b 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/client.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/client.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/dog.py b/samples/client/petstore/python-tornado/petstore_api/models/dog.py
index 39514284d5f2..61acd35cdfe2 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/dog.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/dog.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/dog_all_of.py b/samples/client/petstore/python-tornado/petstore_api/models/dog_all_of.py
index 207103a48745..3a052c3258ae 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/dog_all_of.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/dog_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/enum_arrays.py b/samples/client/petstore/python-tornado/petstore_api/models/enum_arrays.py
index b87cd37456e1..eb4f3ea4ca32 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/enum_arrays.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/enum_arrays.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -119,7 +122,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/enum_class.py b/samples/client/petstore/python-tornado/petstore_api/models/enum_class.py
index 4b11877863ac..79aac3570cb9 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/enum_class.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/enum_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/enum_test.py b/samples/client/petstore/python-tornado/petstore_api/models/enum_test.py
index d1778410dee2..1f3d7cb29b89 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/enum_test.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/enum_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -208,7 +211,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/file.py b/samples/client/petstore/python-tornado/petstore_api/models/file.py
index e40cd04b0149..2c1cccac0e11 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/file.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/file.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -81,7 +84,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/file_schema_test_class.py b/samples/client/petstore/python-tornado/petstore_api/models/file_schema_test_class.py
index d266755d260a..c5a23842d4f6 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/file_schema_test_class.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/file_schema_test_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/format_test.py b/samples/client/petstore/python-tornado/petstore_api/models/format_test.py
index c193f9313e96..452582251a59 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/format_test.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/format_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -463,7 +466,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/has_only_read_only.py b/samples/client/petstore/python-tornado/petstore_api/models/has_only_read_only.py
index dac8cfaff937..7175c2acc721 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/has_only_read_only.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/has_only_read_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/list.py b/samples/client/petstore/python-tornado/petstore_api/models/list.py
index b44257224741..6e1dea4e33b5 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/list.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/list.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/map_test.py b/samples/client/petstore/python-tornado/petstore_api/models/map_test.py
index 406f35db7500..21bd2ccda980 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/map_test.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/map_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -165,7 +168,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/mixed_properties_and_additional_properties_class.py b/samples/client/petstore/python-tornado/petstore_api/models/mixed_properties_and_additional_properties_class.py
index 14428a6536a8..9e727b07d5c7 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/mixed_properties_and_additional_properties_class.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/mixed_properties_and_additional_properties_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/model200_response.py b/samples/client/petstore/python-tornado/petstore_api/models/model200_response.py
index 5c90147467b5..db587fd24e2f 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/model200_response.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/model200_response.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/model_return.py b/samples/client/petstore/python-tornado/petstore_api/models/model_return.py
index 88174ef23083..5354fd56e2ce 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/model_return.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/model_return.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/name.py b/samples/client/petstore/python-tornado/petstore_api/models/name.py
index 528988ebd437..0191a3a934ae 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/name.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/name.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -158,7 +161,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/number_only.py b/samples/client/petstore/python-tornado/petstore_api/models/number_only.py
index ebbcc8996d01..59a252e0bb66 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/number_only.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/order.py b/samples/client/petstore/python-tornado/petstore_api/models/order.py
index 6513d48a3a5e..a267324d0d19 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/order.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/order.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -217,7 +220,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/outer_composite.py b/samples/client/petstore/python-tornado/petstore_api/models/outer_composite.py
index 44124e13c09b..e26160ab4302 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/outer_composite.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/outer_composite.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/outer_enum.py b/samples/client/petstore/python-tornado/petstore_api/models/outer_enum.py
index 77624ba15408..27cdfd1fb791 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/outer_enum.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/outer_enum.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/pet.py b/samples/client/petstore/python-tornado/petstore_api/models/pet.py
index e71589429ca0..22bb4a585e47 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/pet.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/pet.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -219,7 +222,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/read_only_first.py b/samples/client/petstore/python-tornado/petstore_api/models/read_only_first.py
index 3a320fe64f06..c2888eba7500 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/read_only_first.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/read_only_first.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/special_model_name.py b/samples/client/petstore/python-tornado/petstore_api/models/special_model_name.py
index 7669a508789f..4c848e1887c0 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/special_model_name.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/special_model_name.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/tag.py b/samples/client/petstore/python-tornado/petstore_api/models/tag.py
index dbac885ad8e9..a3e6789078d8 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/tag.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/tag.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/type_holder_default.py b/samples/client/petstore/python-tornado/petstore_api/models/type_holder_default.py
index c890f5531927..582b4c8d6dc2 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/type_holder_default.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/type_holder_default.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -188,7 +191,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/type_holder_example.py b/samples/client/petstore/python-tornado/petstore_api/models/type_holder_example.py
index d52425d442ea..268595ed8681 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/type_holder_example.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/type_holder_example.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -215,7 +218,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/user.py b/samples/client/petstore/python-tornado/petstore_api/models/user.py
index b70d84a6b40e..7ae2898f6c5a 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/user.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/user.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -263,7 +266,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/client/petstore/python-tornado/petstore_api/models/xml_item.py b/samples/client/petstore/python-tornado/petstore_api/models/xml_item.py
index d63ab77acfde..5e6fecdd71c8 100644
--- a/samples/client/petstore/python-tornado/petstore_api/models/xml_item.py
+++ b/samples/client/petstore/python-tornado/petstore_api/models/xml_item.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -807,7 +810,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/additional_properties_class.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/additional_properties_class.py
index a846775889f8..f8303e680b26 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/additional_properties_class.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/additional_properties_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/animal.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/animal.py
index 2427f910a97e..1a36f3398fff 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/animal.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/animal.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -117,7 +120,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/api_response.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/api_response.py
index ab5e7999dd2f..bddac1eb10a3 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/api_response.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/api_response.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_of_array_of_number_only.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_of_array_of_number_only.py
index c9b65c7e5315..2975adc20e31 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_of_array_of_number_only.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_of_array_of_number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_of_number_only.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_of_number_only.py
index 870286e0fc08..2a3400e76660 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_of_number_only.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_of_number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_test.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_test.py
index 0e0c17ef1909..5501a637f633 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_test.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/array_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -137,7 +140,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/capitalization.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/capitalization.py
index 064dc2eb2ff5..cb8b0d985842 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/capitalization.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/capitalization.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -211,7 +214,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/cat.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/cat.py
index 3b6e6aa4c2e8..0d9a0b20bf1a 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/cat.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/cat.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/cat_all_of.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/cat_all_of.py
index 7755fd65b0c3..0633bbf58d0d 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/cat_all_of.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/cat_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/category.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/category.py
index c3dd5a4b9a17..ef52dcbf8c91 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/category.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/category.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -106,7 +109,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/class_model.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/class_model.py
index cd9439763d20..84c0de65b472 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/class_model.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/class_model.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/client.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/client.py
index f896b35240c7..8d7c83ecfe6b 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/client.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/client.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/dog.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/dog.py
index 39514284d5f2..61acd35cdfe2 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/dog.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/dog.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/dog_all_of.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/dog_all_of.py
index 207103a48745..3a052c3258ae 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/dog_all_of.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/dog_all_of.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_arrays.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_arrays.py
index b87cd37456e1..eb4f3ea4ca32 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_arrays.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_arrays.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -119,7 +122,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_class.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_class.py
index 4b11877863ac..79aac3570cb9 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_class.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_test.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_test.py
index 09d7d1e3d809..93333df88781 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_test.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/enum_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -285,7 +288,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/file.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/file.py
index e40cd04b0149..2c1cccac0e11 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/file.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/file.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -81,7 +84,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/file_schema_test_class.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/file_schema_test_class.py
index d266755d260a..c5a23842d4f6 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/file_schema_test_class.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/file_schema_test_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/foo.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/foo.py
index 05abc6e9b9fe..cab632f369c4 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/foo.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/foo.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/format_test.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/format_test.py
index a8323ade641e..4e96a7b9175e 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/format_test.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/format_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -522,7 +525,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/has_only_read_only.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/has_only_read_only.py
index dac8cfaff937..7175c2acc721 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/has_only_read_only.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/has_only_read_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/health_check_result.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/health_check_result.py
index cde33f5146a4..64a3f4b2b903 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/health_check_result.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/health_check_result.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -78,7 +81,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/inline_response_default.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/inline_response_default.py
index d9da22a5fd3e..a199122621ff 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/inline_response_default.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/inline_response_default.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/list.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/list.py
index b44257224741..6e1dea4e33b5 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/list.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/list.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/map_test.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/map_test.py
index 406f35db7500..21bd2ccda980 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/map_test.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/map_test.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -165,7 +168,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/mixed_properties_and_additional_properties_class.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/mixed_properties_and_additional_properties_class.py
index 14428a6536a8..9e727b07d5c7 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/mixed_properties_and_additional_properties_class.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/mixed_properties_and_additional_properties_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/model200_response.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/model200_response.py
index 5c90147467b5..db587fd24e2f 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/model200_response.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/model200_response.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/model_return.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/model_return.py
index 88174ef23083..5354fd56e2ce 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/model_return.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/model_return.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/name.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/name.py
index 528988ebd437..0191a3a934ae 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/name.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/name.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -158,7 +161,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/nullable_class.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/nullable_class.py
index 490eb2ba7d01..d36862f8526d 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/nullable_class.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/nullable_class.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -355,7 +358,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/number_only.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/number_only.py
index ebbcc8996d01..59a252e0bb66 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/number_only.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/number_only.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/order.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/order.py
index 6513d48a3a5e..a267324d0d19 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/order.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/order.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -217,7 +220,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_composite.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_composite.py
index 44124e13c09b..e26160ab4302 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_composite.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_composite.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -131,7 +134,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum.py
index 77624ba15408..27cdfd1fb791 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_default_value.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_default_value.py
index aae43db66e67..982e9599d0e5 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_default_value.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_default_value.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_integer.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_integer.py
index d3d9ca3dbf9f..3feec9c5a5a2 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_integer.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_integer.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_integer_default_value.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_integer_default_value.py
index 9e0ed2c1a8b1..6757a4d63674 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_integer_default_value.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_enum_integer_default_value.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -60,7 +63,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_object_with_enum_property.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_object_with_enum_property.py
index 8a50b129a7fb..b9572300b6f6 100644
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_object_with_enum_property.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/outer_object_with_enum_property.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -80,7 +83,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/pet.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/pet.py
index e71589429ca0..22bb4a585e47 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/pet.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/pet.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -219,7 +222,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/read_only_first.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/read_only_first.py
index 3a320fe64f06..c2888eba7500 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/read_only_first.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/read_only_first.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/special_model_name.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/special_model_name.py
index 7669a508789f..4c848e1887c0 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/special_model_name.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/special_model_name.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -79,7 +82,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/tag.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/tag.py
index dbac885ad8e9..a3e6789078d8 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/tag.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/tag.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -105,7 +108,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:
diff --git a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/user.py b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/user.py
index b70d84a6b40e..7ae2898f6c5a 100755
--- a/samples/openapi3/client/petstore/python-legacy/petstore_api/models/user.py
+++ b/samples/openapi3/client/petstore/python-legacy/petstore_api/models/user.py
@@ -10,7 +10,10 @@
 """
 
 
-import inspect
+try:
+    from inspect import getfullargspec
+except ImportError:
+    from inspect import getargspec as getfullargspec
 import pprint
 import re  # noqa: F401
 import six
@@ -263,7 +266,7 @@ def to_dict(self, serialize=False):
 
         def convert(x):
             if hasattr(x, "to_dict"):
-                args = inspect.getargspec(x.to_dict).args
+                args = getfullargspec(x.to_dict).args
                 if len(args) == 1:
                     return x.to_dict()
                 else:

From 3da1999135e8fdde892d67ade26e89559d30cab4 Mon Sep 17 00:00:00 2001
From: Matthew <plague006@users.noreply.github.com>
Date: Mon, 3 May 2021 10:45:55 -0400
Subject: [PATCH 06/18] Fix typo in readme (#9387)

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index c27f86b1531d..2e3ff4b34d77 100644
--- a/README.md
+++ b/README.md
@@ -562,7 +562,7 @@ When code is generated from this project, it shall be considered **AS IS** and o
 
 ### [3.5 - IDE Integration](#table-of-contents)
 
-Here is a list of community-conitributed IDE plug-ins that integrate with OpenAPI Generator:
+Here is a list of community-contributed IDE plug-ins that integrate with OpenAPI Generator:
 
 - Eclipse: [Codewind OpenAPI Tools for Eclipse](https://www.eclipse.org/codewind/open-api-tools-for-eclipse.html) by [IBM](https://www.ibm.com)
 - IntelliJ IDEA: [OpenAPI Generator](https://plugins.jetbrains.com/plugin/8433-openapi-generator) by [Jim Schubert](https://jimschubert.us/#/)

From d21743e9e59114814d703e8ff4b42598ba885138 Mon Sep 17 00:00:00 2001
From: Stefan Wendt <stefanwendt@posteo.de>
Date: Mon, 3 May 2021 18:15:52 +0200
Subject: [PATCH 07/18] [TypeScript-fetch] Fix issue 9360 (#9362)

* [TypeScript] Fix misplaced parentheses

* [TypeScript] Run PR relevant scripts

* [TypeScript] ensure up to date

* Revert "[TypeScript] ensure up to date"

This reverts commit 320ec45f

* Revert "[TypeScript] Run PR relevant scripts"

This reverts commit 23cda753

Co-authored-by: Stefan Wendt <stefan.wendt@isax.com>
---
 .../src/main/resources/typescript-fetch/modelGeneric.mustache   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache b/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache
index 00d4e010fa0d..3036e3662907 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache
@@ -109,7 +109,7 @@ export function {{classname}}ToJSON(value?: {{classname}} | null): any {
         {{^isPrimitiveType}}
         {{#isArray}}
         {{#uniqueItems}}
-        '{{baseName}}': {{^required}}value.{{name}} === undefined ? undefined : {{/required}}({{#isNullable}}value.{{name}} === null ? null : {{/isNullable}}Array.from((value.{{name}} as Set<any>).map({{#items}}{{datatype}}{{/items}}ToJSON))),
+        '{{baseName}}': {{^required}}value.{{name}} === undefined ? undefined : {{/required}}({{#isNullable}}value.{{name}} === null ? null : {{/isNullable}}Array.from(value.{{name}} as Set<any>).map({{#items}}{{datatype}}{{/items}}ToJSON)),
         {{/uniqueItems}}
         {{^uniqueItems}}
         '{{baseName}}': {{^required}}value.{{name}} === undefined ? undefined : {{/required}}({{#isNullable}}value.{{name}} === null ? null : {{/isNullable}}(value.{{name}} as Array<any>).map({{#items}}{{datatype}}{{/items}}ToJSON)),

From e9fa93688617d0cb602c5805c48d80750d570289 Mon Sep 17 00:00:00 2001
From: Luca Mazzanti <lucamazzanti83@gmail.com>
Date: Tue, 4 May 2021 17:58:20 +0200
Subject: [PATCH 08/18] [csharp][netcore-httpclient] Refactor of constructors:
 removed obsolete attribute (#9373)

* Removed obsolete attribute on constructors without HttpClient prameter

* add clickable link in the tooltip

* update doc, add tests

Co-authored-by: William Cheng <wing328hk@gmail.com>
---
 .../resources/csharp-netcore/README.mustache  | 11 +++
 .../resources/csharp-netcore/api_doc.mustache | 11 +++
 .../libraries/httpclient/ApiClient.mustache   |  6 +-
 .../libraries/httpclient/api.mustache         |  9 +-
 .../OpenAPIClient-httpclient/README.md        |  6 +-
 .../docs/AnotherFakeApi.md                    |  6 +-
 .../docs/DefaultApi.md                        |  6 +-
 .../OpenAPIClient-httpclient/docs/FakeApi.md  | 90 +++++++++++++++----
 .../docs/FakeClassnameTags123Api.md           |  6 +-
 .../OpenAPIClient-httpclient/docs/PetApi.md   | 54 +++++++++--
 .../OpenAPIClient-httpclient/docs/StoreApi.md | 24 ++++-
 .../OpenAPIClient-httpclient/docs/UserApi.md  | 48 ++++++++--
 .../Org.OpenAPITools.Test/Api/PetApiTests.cs  | 12 ++-
 .../Org.OpenAPITools/Api/AnotherFakeApi.cs    |  9 +-
 .../src/Org.OpenAPITools/Api/DefaultApi.cs    |  9 +-
 .../src/Org.OpenAPITools/Api/FakeApi.cs       |  9 +-
 .../Api/FakeClassnameTags123Api.cs            |  9 +-
 .../src/Org.OpenAPITools/Api/PetApi.cs        |  9 +-
 .../src/Org.OpenAPITools/Api/StoreApi.cs      |  9 +-
 .../src/Org.OpenAPITools/Api/UserApi.cs       |  9 +-
 .../src/Org.OpenAPITools/Client/ApiClient.cs  |  6 +-
 21 files changed, 287 insertions(+), 71 deletions(-)

diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/README.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/README.mustache
index c5f3c0eadfa9..b15d2a25bf19 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/README.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/README.mustache
@@ -137,6 +137,9 @@ services.AddHttpClient<YourApiClass>(httpClient =>
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+{{#useHttpClient}}
+using System.Net.Http;
+{{/useHttpClient}}
 using {{packageName}}.{{apiPackage}};
 using {{packageName}}.Client;
 using {{packageName}}.{{modelPackage}};
@@ -174,7 +177,15 @@ namespace Example
             {{/authMethods}}
 
             {{/hasAuthMethods}}
+            {{#useHttpClient}}
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new {{classname}}(httpClient, config, httpClientHandler);
+            {{/useHttpClient}}
+            {{^useHttpClient}}
             var apiInstance = new {{classname}}(config);
+            {{/useHttpClient}}
             {{#allParams}}
             {{#isPrimitiveType}}
             var {{paramName}} = {{{example}}};  // {{{dataType}}} | {{{description}}}{{^required}} (optional) {{/required}}{{#defaultValue}} (default to {{{.}}}){{/defaultValue}}
diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/api_doc.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/api_doc.mustache
index 0fd9f8790611..d12ee22ea388 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/api_doc.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/api_doc.mustache
@@ -22,6 +22,9 @@ Method | HTTP request | Description
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+{{#useHttpClient}}
+using System.Net.Http;
+{{/useHttpClient}}
 using {{packageName}}.{{apiPackage}};
 using {{packageName}}.Client;
 using {{packageName}}.{{modelPackage}};
@@ -58,7 +61,15 @@ namespace Example
             {{/authMethods}}
 
             {{/hasAuthMethods}}
+            {{#useHttpClient}}
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new {{classname}}(httpClient, config, httpClientHandler);
+            {{/useHttpClient}}
+            {{^useHttpClient}}
             var apiInstance = new {{classname}}(config);
+            {{/useHttpClient}}
             {{#allParams}}
             {{#isPrimitiveType}}
             var {{paramName}} = {{{example}}};  // {{{dataType}}} | {{{description}}}{{^required}} (optional) {{/required}}{{#defaultValue}} (default to {{{.}}}){{/defaultValue}}
diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/ApiClient.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/ApiClient.mustache
index 619bcb6bfbb5..640e0335c119 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/ApiClient.mustache
@@ -191,8 +191,9 @@ namespace {{packageName}}.Client
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ApiClient" />, defaulting to the global configurations' base url.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public ApiClient() :
                  this({{packageName}}.Client.GlobalConfiguration.Instance.BasePath)
         {    
@@ -200,10 +201,11 @@ namespace {{packageName}}.Client
         
         /// <summary>
         /// Initializes a new instance of the <see cref="ApiClient" />.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="basePath">The target service's base path in URL format.</param>
         /// <exception cref="ArgumentException"></exception>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public ApiClient(String basePath)
         {    
             if (string.IsNullOrEmpty(basePath)) throw new ArgumentException("basePath cannot be empty");
diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/api.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/api.mustache
index efa52cfbd418..0a3389d0a450 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/api.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/libraries/httpclient/api.mustache
@@ -106,20 +106,22 @@ namespace {{packageName}}.{{apiPackage}}
 
         /// <summary>
         /// Initializes a new instance of the <see cref="{{classname}}"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public {{classname}}() : this((string)null)
         {
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="{{classname}}"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="basePath">The target service's base path in URL format.</param>
         /// <exception cref="ArgumentException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public {{classname}}(String basePath)
         {
             this.Configuration = {{packageName}}.Client.Configuration.MergeConfigurations(
@@ -136,11 +138,12 @@ namespace {{packageName}}.{{apiPackage}}
 
         /// <summary>
         /// Initializes a new instance of the <see cref="{{classname}}"/> class using Configuration object.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="configuration">An instance of Configuration.</param>
         /// <exception cref="ArgumentNullException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public {{classname}}({{packageName}}.Client.Configuration configuration)
         {
             if (configuration == null) throw new ArgumentNullException("configuration");
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/README.md b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/README.md
index e16da183ea85..48379909c58f 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/README.md
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/README.md
@@ -83,6 +83,7 @@ services.AddHttpClient<YourApiClass>(httpClient =>
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -96,7 +97,10 @@ namespace Example
 
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new AnotherFakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new AnotherFakeApi(httpClient, config, httpClientHandler);
             var modelClient = new ModelClient(); // ModelClient | client model
 
             try
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/AnotherFakeApi.md b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/AnotherFakeApi.md
index 93fca7e408ac..83cdaf2ae930 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/AnotherFakeApi.md
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/AnotherFakeApi.md
@@ -19,6 +19,7 @@ To test special tags and operation ID starting with number
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -31,7 +32,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new AnotherFakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new AnotherFakeApi(httpClient, config, httpClientHandler);
             var modelClient = new ModelClient(); // ModelClient | client model
 
             try
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/DefaultApi.md b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/DefaultApi.md
index 6f5de6b68511..ec7241832837 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/DefaultApi.md
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/DefaultApi.md
@@ -17,6 +17,7 @@ Method | HTTP request | Description
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -29,7 +30,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new DefaultApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new DefaultApi(httpClient, config, httpClientHandler);
 
             try
             {
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/FakeApi.md b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/FakeApi.md
index af8d565abfb1..947fbb114ef3 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/FakeApi.md
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/FakeApi.md
@@ -31,6 +31,7 @@ Health check endpoint
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -43,7 +44,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
 
             try
             {
@@ -98,6 +102,7 @@ Test serialization of outer boolean types
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -110,7 +115,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var body = true;  // bool? | Input boolean as post body (optional) 
 
             try
@@ -168,6 +176,7 @@ Test serialization of object with outer number type
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -180,7 +189,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var outerComposite = new OuterComposite(); // OuterComposite | Input composite as post body (optional) 
 
             try
@@ -238,6 +250,7 @@ Test serialization of outer number types
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -250,7 +263,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var body = 8.14;  // decimal? | Input number as post body (optional) 
 
             try
@@ -308,6 +324,7 @@ Test serialization of outer string types
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -320,7 +337,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var body = body_example;  // string | Input string as post body (optional) 
 
             try
@@ -376,6 +396,7 @@ Array of Enums
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -388,7 +409,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
 
             try
             {
@@ -443,6 +467,7 @@ For this test, the body for this request much reference a schema named `File`.
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -455,7 +480,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var fileSchemaTestClass = new FileSchemaTestClass(); // FileSchemaTestClass | 
 
             try
@@ -510,6 +538,7 @@ No authorization required
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -522,7 +551,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var query = query_example;  // string | 
             var user = new User(); // User | 
 
@@ -581,6 +613,7 @@ To test \"client\" model
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -593,7 +626,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var modelClient = new ModelClient(); // ModelClient | client model
 
             try
@@ -652,6 +688,7 @@ Fake endpoint for testing various parameters 假端點 偽のエンドポイン
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -668,7 +705,10 @@ namespace Example
             config.Username = "YOUR_USERNAME";
             config.Password = "YOUR_PASSWORD";
 
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var number = 8.14;  // decimal | None
             var _double = 1.2D;  // double | None
             var patternWithoutDelimiter = patternWithoutDelimiter_example;  // string | None
@@ -753,6 +793,7 @@ To test enum parameters
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -765,7 +806,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var enumHeaderStringArray = enumHeaderStringArray_example;  // List<string> | Header parameter enum test (string array) (optional) 
             var enumHeaderString = enumHeaderString_example;  // string | Header parameter enum test (string) (optional)  (default to -efg)
             var enumQueryStringArray = enumQueryStringArray_example;  // List<string> | Query parameter enum test (string array) (optional) 
@@ -838,6 +882,7 @@ Fake endpoint to test group parameters (optional)
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -853,7 +898,10 @@ namespace Example
             // Configure Bearer token for authorization: bearer_test
             config.AccessToken = "YOUR_BEARER_TOKEN";
 
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var requiredStringGroup = 56;  // int | Required String in group parameters
             var requiredBooleanGroup = true;  // bool | Required Boolean in group parameters
             var requiredInt64Group = 789;  // long | Required Integer in group parameters
@@ -919,6 +967,7 @@ test inline additionalProperties
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -931,7 +980,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var requestBody = new Dictionary<string, string>(); // Dictionary<string, string> | request body
 
             try
@@ -987,6 +1039,7 @@ test json serialization of form data
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -999,7 +1052,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var param = param_example;  // string | field1
             var param2 = param2_example;  // string | field2
 
@@ -1059,6 +1115,7 @@ To test the collection format in query parameters
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -1071,7 +1128,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new FakeApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeApi(httpClient, config, httpClientHandler);
             var pipe = new List<string>(); // List<string> | 
             var ioutil = new List<string>(); // List<string> | 
             var http = new List<string>(); // List<string> | 
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/FakeClassnameTags123Api.md b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/FakeClassnameTags123Api.md
index 13235fbd10f0..4c748ad71c8e 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/FakeClassnameTags123Api.md
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/FakeClassnameTags123Api.md
@@ -19,6 +19,7 @@ To test class name in snake case
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -36,7 +37,10 @@ namespace Example
             // Uncomment below to setup prefix (e.g. Bearer) for API key, if needed
             // config.AddApiKeyPrefix("api_key_query", "Bearer");
 
-            var apiInstance = new FakeClassnameTags123Api(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new FakeClassnameTags123Api(httpClient, config, httpClientHandler);
             var modelClient = new ModelClient(); // ModelClient | client model
 
             try
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/PetApi.md b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/PetApi.md
index 47820f406dd2..9f4ec108d05f 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/PetApi.md
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/PetApi.md
@@ -25,6 +25,7 @@ Add a new pet to the store
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -40,7 +41,10 @@ namespace Example
             // Configure OAuth2 access token for authorization: petstore_auth
             config.AccessToken = "YOUR_ACCESS_TOKEN";
 
-            var apiInstance = new PetApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
             var pet = new Pet(); // Pet | Pet object that needs to be added to the store
 
             try
@@ -96,6 +100,7 @@ Deletes a pet
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -111,7 +116,10 @@ namespace Example
             // Configure OAuth2 access token for authorization: petstore_auth
             config.AccessToken = "YOUR_ACCESS_TOKEN";
 
-            var apiInstance = new PetApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
             var petId = 789;  // long | Pet id to delete
             var apiKey = apiKey_example;  // string |  (optional) 
 
@@ -171,6 +179,7 @@ Multiple status values can be provided with comma separated strings
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -186,7 +195,10 @@ namespace Example
             // Configure OAuth2 access token for authorization: petstore_auth
             config.AccessToken = "YOUR_ACCESS_TOKEN";
 
-            var apiInstance = new PetApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
             var status = status_example;  // List<string> | Status values that need to be considered for filter
 
             try
@@ -246,6 +258,7 @@ Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -261,7 +274,10 @@ namespace Example
             // Configure OAuth2 access token for authorization: petstore_auth
             config.AccessToken = "YOUR_ACCESS_TOKEN";
 
-            var apiInstance = new PetApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
             var tags = new List<string>(); // List<string> | Tags to filter by
 
             try
@@ -321,6 +337,7 @@ Returns a single pet
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -338,7 +355,10 @@ namespace Example
             // Uncomment below to setup prefix (e.g. Bearer) for API key, if needed
             // config.AddApiKeyPrefix("api_key", "Bearer");
 
-            var apiInstance = new PetApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
             var petId = 789;  // long | ID of pet to return
 
             try
@@ -397,6 +417,7 @@ Update an existing pet
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -412,7 +433,10 @@ namespace Example
             // Configure OAuth2 access token for authorization: petstore_auth
             config.AccessToken = "YOUR_ACCESS_TOKEN";
 
-            var apiInstance = new PetApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
             var pet = new Pet(); // Pet | Pet object that needs to be added to the store
 
             try
@@ -470,6 +494,7 @@ Updates a pet in the store with form data
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -485,7 +510,10 @@ namespace Example
             // Configure OAuth2 access token for authorization: petstore_auth
             config.AccessToken = "YOUR_ACCESS_TOKEN";
 
-            var apiInstance = new PetApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
             var petId = 789;  // long | ID of pet that needs to be updated
             var name = name_example;  // string | Updated name of the pet (optional) 
             var status = status_example;  // string | Updated status of the pet (optional) 
@@ -545,6 +573,7 @@ uploads an image
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -560,7 +589,10 @@ namespace Example
             // Configure OAuth2 access token for authorization: petstore_auth
             config.AccessToken = "YOUR_ACCESS_TOKEN";
 
-            var apiInstance = new PetApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
             var petId = 789;  // long | ID of pet to update
             var additionalMetadata = additionalMetadata_example;  // string | Additional data to pass to server (optional) 
             var file = BINARY_DATA_HERE;  // System.IO.Stream | file to upload (optional) 
@@ -621,6 +653,7 @@ uploads an image (required)
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -636,7 +669,10 @@ namespace Example
             // Configure OAuth2 access token for authorization: petstore_auth
             config.AccessToken = "YOUR_ACCESS_TOKEN";
 
-            var apiInstance = new PetApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new PetApi(httpClient, config, httpClientHandler);
             var petId = 789;  // long | ID of pet to update
             var requiredFile = BINARY_DATA_HERE;  // System.IO.Stream | file to upload
             var additionalMetadata = additionalMetadata_example;  // string | Additional data to pass to server (optional) 
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/StoreApi.md b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/StoreApi.md
index 24e2480d5deb..248bf31f849c 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/StoreApi.md
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/StoreApi.md
@@ -22,6 +22,7 @@ For valid response try integer IDs with value < 1000. Anything above 1000 or non
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -34,7 +35,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new StoreApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new StoreApi(httpClient, config, httpClientHandler);
             var orderId = orderId_example;  // string | ID of the order that needs to be deleted
 
             try
@@ -93,6 +97,7 @@ Returns a map of status codes to quantities
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -110,7 +115,10 @@ namespace Example
             // Uncomment below to setup prefix (e.g. Bearer) for API key, if needed
             // config.AddApiKeyPrefix("api_key", "Bearer");
 
-            var apiInstance = new StoreApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new StoreApi(httpClient, config, httpClientHandler);
 
             try
             {
@@ -165,6 +173,7 @@ For valid response try integer IDs with value <= 5 or > 10. Other values will ge
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -177,7 +186,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new StoreApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new StoreApi(httpClient, config, httpClientHandler);
             var orderId = 789;  // long | ID of pet that needs to be fetched
 
             try
@@ -236,6 +248,7 @@ Place an order for a pet
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -248,7 +261,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new StoreApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new StoreApi(httpClient, config, httpClientHandler);
             var order = new Order(); // Order | order placed for purchasing the pet
 
             try
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/UserApi.md b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/UserApi.md
index aa12c26c69f1..417d9002cf94 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/UserApi.md
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/docs/UserApi.md
@@ -26,6 +26,7 @@ This can only be done by the logged in user.
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -38,7 +39,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new UserApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new UserApi(httpClient, config, httpClientHandler);
             var user = new User(); // User | Created user object
 
             try
@@ -94,6 +98,7 @@ Creates list of users with given input array
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -106,7 +111,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new UserApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new UserApi(httpClient, config, httpClientHandler);
             var user = new List<User>(); // List<User> | List of user object
 
             try
@@ -162,6 +170,7 @@ Creates list of users with given input array
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -174,7 +183,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new UserApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new UserApi(httpClient, config, httpClientHandler);
             var user = new List<User>(); // List<User> | List of user object
 
             try
@@ -232,6 +244,7 @@ This can only be done by the logged in user.
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -244,7 +257,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new UserApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new UserApi(httpClient, config, httpClientHandler);
             var username = username_example;  // string | The name that needs to be deleted
 
             try
@@ -301,6 +317,7 @@ Get user by user name
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -313,7 +330,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new UserApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new UserApi(httpClient, config, httpClientHandler);
             var username = username_example;  // string | The name that needs to be fetched. Use user1 for testing.
 
             try
@@ -372,6 +392,7 @@ Logs user into the system
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -384,7 +405,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new UserApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new UserApi(httpClient, config, httpClientHandler);
             var username = username_example;  // string | The user name for login
             var password = password_example;  // string | The password for login in clear text
 
@@ -444,6 +468,7 @@ Logs out current logged in user session
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -456,7 +481,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new UserApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new UserApi(httpClient, config, httpClientHandler);
 
             try
             {
@@ -510,6 +538,7 @@ This can only be done by the logged in user.
 ```csharp
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Net.Http;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Model;
@@ -522,7 +551,10 @@ namespace Example
         {
             Configuration config = new Configuration();
             config.BasePath = "http://petstore.swagger.io:80/v2";
-            var apiInstance = new UserApi(config);
+            // create instances of HttpClient, HttpClientHandler to be reused later with different Api classes
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            var apiInstance = new UserApi(httpClient, config, httpClientHandler);
             var username = username_example;  // string | name that need to be deleted
             var user = new User(); // User | Updated user object
 
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools.Test/Api/PetApiTests.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
index eca3164a17fd..04ef8503f955 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools.Test/Api/PetApiTests.cs
@@ -16,6 +16,8 @@
 using System.Reflection;
 using Xunit;
 
+using System.Net.Http;
+
 using Org.OpenAPITools.Client;
 using Org.OpenAPITools.Api;
 using Org.OpenAPITools.Model;
@@ -73,8 +75,10 @@ private byte[] GetBytes(string str)
         }
 
         public PetApiTests()
-        { 
-            instance = new PetApi();
+        {
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            instance = new PetApi(httpClient, httpClientHandler);
 
             // create pet
             Pet p = createPet();
@@ -153,7 +157,9 @@ public void GetPetByIdTest()
             c1.Timeout = 10000;
             c1.UserAgent = "TEST_USER_AGENT";
 
-            PetApi petApi = new PetApi(c1);
+            HttpClient httpClient = new HttpClient();
+            HttpClientHandler httpClientHandler = new HttpClientHandler();
+            PetApi petApi = new PetApi(httpClient, c1, httpClientHandler);
             Pet response = petApi.GetPetById(petId);
             Assert.IsType<Pet>(response);
 
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/AnotherFakeApi.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/AnotherFakeApi.cs
index 83a938cf365d..8498781b05c4 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/AnotherFakeApi.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/AnotherFakeApi.cs
@@ -100,20 +100,22 @@ public partial class AnotherFakeApi : IDisposable, IAnotherFakeApi
 
         /// <summary>
         /// Initializes a new instance of the <see cref="AnotherFakeApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public AnotherFakeApi() : this((string)null)
         {
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="AnotherFakeApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="basePath">The target service's base path in URL format.</param>
         /// <exception cref="ArgumentException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public AnotherFakeApi(String basePath)
         {
             this.Configuration = Org.OpenAPITools.Client.Configuration.MergeConfigurations(
@@ -128,11 +130,12 @@ public AnotherFakeApi(String basePath)
 
         /// <summary>
         /// Initializes a new instance of the <see cref="AnotherFakeApi"/> class using Configuration object.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="configuration">An instance of Configuration.</param>
         /// <exception cref="ArgumentNullException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public AnotherFakeApi(Org.OpenAPITools.Client.Configuration configuration)
         {
             if (configuration == null) throw new ArgumentNullException("configuration");
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/DefaultApi.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/DefaultApi.cs
index 84b91a9a1712..299f2875b21c 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/DefaultApi.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/DefaultApi.cs
@@ -93,20 +93,22 @@ public partial class DefaultApi : IDisposable, IDefaultApi
 
         /// <summary>
         /// Initializes a new instance of the <see cref="DefaultApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public DefaultApi() : this((string)null)
         {
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="DefaultApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="basePath">The target service's base path in URL format.</param>
         /// <exception cref="ArgumentException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public DefaultApi(String basePath)
         {
             this.Configuration = Org.OpenAPITools.Client.Configuration.MergeConfigurations(
@@ -121,11 +123,12 @@ public DefaultApi(String basePath)
 
         /// <summary>
         /// Initializes a new instance of the <see cref="DefaultApi"/> class using Configuration object.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="configuration">An instance of Configuration.</param>
         /// <exception cref="ArgumentNullException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public DefaultApi(Org.OpenAPITools.Client.Configuration configuration)
         {
             if (configuration == null) throw new ArgumentNullException("configuration");
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/FakeApi.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/FakeApi.cs
index 305a59a6b5bd..66f86c619fcf 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/FakeApi.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/FakeApi.cs
@@ -817,20 +817,22 @@ public partial class FakeApi : IDisposable, IFakeApi
 
         /// <summary>
         /// Initializes a new instance of the <see cref="FakeApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public FakeApi() : this((string)null)
         {
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="FakeApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="basePath">The target service's base path in URL format.</param>
         /// <exception cref="ArgumentException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public FakeApi(String basePath)
         {
             this.Configuration = Org.OpenAPITools.Client.Configuration.MergeConfigurations(
@@ -845,11 +847,12 @@ public FakeApi(String basePath)
 
         /// <summary>
         /// Initializes a new instance of the <see cref="FakeApi"/> class using Configuration object.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="configuration">An instance of Configuration.</param>
         /// <exception cref="ArgumentNullException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public FakeApi(Org.OpenAPITools.Client.Configuration configuration)
         {
             if (configuration == null) throw new ArgumentNullException("configuration");
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/FakeClassnameTags123Api.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/FakeClassnameTags123Api.cs
index f9c9d3b33cea..efec560791ec 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/FakeClassnameTags123Api.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/FakeClassnameTags123Api.cs
@@ -100,20 +100,22 @@ public partial class FakeClassnameTags123Api : IDisposable, IFakeClassnameTags12
 
         /// <summary>
         /// Initializes a new instance of the <see cref="FakeClassnameTags123Api"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public FakeClassnameTags123Api() : this((string)null)
         {
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="FakeClassnameTags123Api"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="basePath">The target service's base path in URL format.</param>
         /// <exception cref="ArgumentException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public FakeClassnameTags123Api(String basePath)
         {
             this.Configuration = Org.OpenAPITools.Client.Configuration.MergeConfigurations(
@@ -128,11 +130,12 @@ public FakeClassnameTags123Api(String basePath)
 
         /// <summary>
         /// Initializes a new instance of the <see cref="FakeClassnameTags123Api"/> class using Configuration object.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="configuration">An instance of Configuration.</param>
         /// <exception cref="ArgumentNullException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public FakeClassnameTags123Api(Org.OpenAPITools.Client.Configuration configuration)
         {
             if (configuration == null) throw new ArgumentNullException("configuration");
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/PetApi.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/PetApi.cs
index b43e10ad1ffb..7f9a79b6bb3d 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/PetApi.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/PetApi.cs
@@ -462,20 +462,22 @@ public partial class PetApi : IDisposable, IPetApi
 
         /// <summary>
         /// Initializes a new instance of the <see cref="PetApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public PetApi() : this((string)null)
         {
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="PetApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="basePath">The target service's base path in URL format.</param>
         /// <exception cref="ArgumentException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public PetApi(String basePath)
         {
             this.Configuration = Org.OpenAPITools.Client.Configuration.MergeConfigurations(
@@ -490,11 +492,12 @@ public PetApi(String basePath)
 
         /// <summary>
         /// Initializes a new instance of the <see cref="PetApi"/> class using Configuration object.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="configuration">An instance of Configuration.</param>
         /// <exception cref="ArgumentNullException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public PetApi(Org.OpenAPITools.Client.Configuration configuration)
         {
             if (configuration == null) throw new ArgumentNullException("configuration");
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/StoreApi.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/StoreApi.cs
index f174edf50628..d7b0b43698af 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/StoreApi.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/StoreApi.cs
@@ -225,20 +225,22 @@ public partial class StoreApi : IDisposable, IStoreApi
 
         /// <summary>
         /// Initializes a new instance of the <see cref="StoreApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public StoreApi() : this((string)null)
         {
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="StoreApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="basePath">The target service's base path in URL format.</param>
         /// <exception cref="ArgumentException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public StoreApi(String basePath)
         {
             this.Configuration = Org.OpenAPITools.Client.Configuration.MergeConfigurations(
@@ -253,11 +255,12 @@ public StoreApi(String basePath)
 
         /// <summary>
         /// Initializes a new instance of the <see cref="StoreApi"/> class using Configuration object.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="configuration">An instance of Configuration.</param>
         /// <exception cref="ArgumentNullException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public StoreApi(Org.OpenAPITools.Client.Configuration configuration)
         {
             if (configuration == null) throw new ArgumentNullException("configuration");
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/UserApi.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/UserApi.cs
index 0426a00745eb..9b4826f955eb 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/UserApi.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Api/UserApi.cs
@@ -397,20 +397,22 @@ public partial class UserApi : IDisposable, IUserApi
 
         /// <summary>
         /// Initializes a new instance of the <see cref="UserApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public UserApi() : this((string)null)
         {
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="UserApi"/> class.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="basePath">The target service's base path in URL format.</param>
         /// <exception cref="ArgumentException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public UserApi(String basePath)
         {
             this.Configuration = Org.OpenAPITools.Client.Configuration.MergeConfigurations(
@@ -425,11 +427,12 @@ public UserApi(String basePath)
 
         /// <summary>
         /// Initializes a new instance of the <see cref="UserApi"/> class using Configuration object.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="configuration">An instance of Configuration.</param>
         /// <exception cref="ArgumentNullException"></exception>
         /// <returns></returns>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public UserApi(Org.OpenAPITools.Client.Configuration configuration)
         {
             if (configuration == null) throw new ArgumentNullException("configuration");
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs
index 26695dd48d45..9bdab1cf4c87 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/ApiClient.cs
@@ -191,8 +191,9 @@ public partial class ApiClient : IDisposable, ISynchronousClient, IAsynchronousC
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ApiClient" />, defaulting to the global configurations' base url.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public ApiClient() :
                  this(Org.OpenAPITools.Client.GlobalConfiguration.Instance.BasePath)
         {    
@@ -200,10 +201,11 @@ public ApiClient() :
         
         /// <summary>
         /// Initializes a new instance of the <see cref="ApiClient" />.
+        /// **IMPORTANT** This will also create an istance of HttpClient, which is less than ideal.
+        /// It's better to reuse the <see href="https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests#issues-with-the-original-httpclient-class-available-in-net">HttpClient and HttpClientHander</see>.
         /// </summary>
         /// <param name="basePath">The target service's base path in URL format.</param>
         /// <exception cref="ArgumentException"></exception>
-        [Obsolete("Constructors without HttpClient have non-trivial drawbacks and are thus considered deprecated. Check README.md for details.")]
         public ApiClient(String basePath)
         {    
             if (string.IsNullOrEmpty(basePath)) throw new ArgumentException("basePath cannot be empty");

From 4d2b022619ccf85fe30f9dbf33f7c12e24933abf Mon Sep 17 00:00:00 2001
From: shylacs <shyla.cs@gmail.com>
Date: Tue, 4 May 2021 09:08:15 -0700
Subject: [PATCH 09/18] Add VMware to users list (#9388)

* Add VMware to users list

LMK if I can provide the png for company logo. I tried uploading to img folder and could not.

* add logo, update readme

Co-authored-by: William Cheng <wing328hk@gmail.com>
---
 README.md                               |   1 +
 website/src/dynamic/users.yml           |   5 +++++
 website/static/img/companies/vmware.png | Bin 0 -> 3140 bytes
 3 files changed, 6 insertions(+)
 create mode 100644 website/static/img/companies/vmware.png

diff --git a/README.md b/README.md
index 2e3ff4b34d77..c994f615fa62 100644
--- a/README.md
+++ b/README.md
@@ -666,6 +666,7 @@ Here are some companies/projects (alphabetical order) using OpenAPI Generator in
 - [Twitter](https://twitter.com)
 - [unblu inc.](https://www.unblu.com/)
 - [Veamly](https://www.veamly.com/)
+- [VMWare](https://www.vmware.com/)
 - [wbt-solutions](https://www.wbt-solutions.de/)
 - [Woleet](https://www.woleet.io/)
 - [WSO2](https://wso2.com/)
diff --git a/website/src/dynamic/users.yml b/website/src/dynamic/users.yml
index 38104947192d..7b955bfe3372 100644
--- a/website/src/dynamic/users.yml
+++ b/website/src/dynamic/users.yml
@@ -453,6 +453,11 @@
   image: "img/companies/viadee.jpg"
   infoLink: "https://www.viadee.de"
   pinned: false
+-
+  caption: "VMware"
+  image: "img/companies/vmware.png"
+  infoLink: "https://www.vmware.com/"
+  pinned: false
 -
   caption: Vonage
   image: "img/companies/vonage.png"
diff --git a/website/static/img/companies/vmware.png b/website/static/img/companies/vmware.png
new file mode 100644
index 0000000000000000000000000000000000000000..7e697256a9e1771186befa93dea15f8564c7e95b
GIT binary patch
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From 8f5639554e96a9beaf0b4c87b9dac52afcc1ef83 Mon Sep 17 00:00:00 2001
From: Julian G <23147553+JulianGmp@users.noreply.github.com>
Date: Wed, 5 May 2021 10:52:47 +0200
Subject: [PATCH 10/18] [C++] [Pistache] Model validation, general overhaul
 (#9251)

* overhaul pistache templates

* fix function signature in model-source
return type now aligns with definition in model-header

* use default keyword for destructors

* generate pistache samples

* move bin/configs/other/cpp-pistache-server-cpp-pistache.yaml to bin/configs/cpp-pistache-server-cpp-pistache.yaml

* Only generate validation body if necessary

* generate pistache samples
---
 .../cpp-pistache-server-cpp-pistache.yaml     |   0
 .../languages/CppPistacheServerCodegen.java   |   1 +
 .../cpp-pistache-server/api-header.mustache   |  37 ++--
 .../api-impl-header.mustache                  |  15 +-
 .../api-impl-source.mustache                  |   7 +-
 .../cpp-pistache-server/api-source.mustache   |  60 ++++--
 .../helpers-header.mustache                   |  86 ++++++--
 .../helpers-source.mustache                   |  76 +++++--
 .../cpp-pistache-server/model-header.mustache |  31 ++-
 .../cpp-pistache-server/model-source.mustache |  78 +++++--
 .../model-struct-header.mustache              |  11 +-
 .../model-struct-source.mustache              |   9 +-
 .../model-validation-body.mustache            | 124 +++++++++++
 .../cpp-pistache/.openapi-generator/VERSION   |   2 +-
 .../petstore/cpp-pistache/api/PetApi.cpp      | 174 ++++++++++------
 .../server/petstore/cpp-pistache/api/PetApi.h |  45 ++--
 .../petstore/cpp-pistache/api/StoreApi.cpp    | 106 ++++++----
 .../petstore/cpp-pistache/api/StoreApi.h      |  39 ++--
 .../petstore/cpp-pistache/api/UserApi.cpp     | 194 ++++++++++++------
 .../petstore/cpp-pistache/api/UserApi.h       |  45 ++--
 .../petstore/cpp-pistache/impl/PetApiImpl.cpp |   5 +-
 .../petstore/cpp-pistache/impl/PetApiImpl.h   |  17 +-
 .../cpp-pistache/impl/StoreApiImpl.cpp        |   5 +-
 .../petstore/cpp-pistache/impl/StoreApiImpl.h |  17 +-
 .../cpp-pistache/impl/UserApiImpl.cpp         |   5 +-
 .../petstore/cpp-pistache/impl/UserApiImpl.h  |  17 +-
 .../cpp-pistache/model/ApiResponse.cpp        |  59 +++++-
 .../petstore/cpp-pistache/model/ApiResponse.h |  31 ++-
 .../petstore/cpp-pistache/model/Category.cpp  |  55 ++++-
 .../petstore/cpp-pistache/model/Category.h    |  31 ++-
 .../petstore/cpp-pistache/model/Helpers.cpp   |  78 +++++--
 .../petstore/cpp-pistache/model/Helpers.h     |  88 ++++++--
 .../petstore/cpp-pistache/model/Order.cpp     |  71 ++++++-
 .../petstore/cpp-pistache/model/Order.h       |  31 ++-
 .../petstore/cpp-pistache/model/Pet.cpp       | 117 +++++++++--
 .../server/petstore/cpp-pistache/model/Pet.h  |  35 ++--
 .../petstore/cpp-pistache/model/Tag.cpp       |  55 ++++-
 .../server/petstore/cpp-pistache/model/Tag.h  |  31 ++-
 .../petstore/cpp-pistache/model/User.cpp      |  79 ++++++-
 .../server/petstore/cpp-pistache/model/User.h |  31 ++-
 40 files changed, 1461 insertions(+), 537 deletions(-)
 rename bin/configs/{other => }/cpp-pistache-server-cpp-pistache.yaml (100%)
 create mode 100644 modules/openapi-generator/src/main/resources/cpp-pistache-server/model-validation-body.mustache

diff --git a/bin/configs/other/cpp-pistache-server-cpp-pistache.yaml b/bin/configs/cpp-pistache-server-cpp-pistache.yaml
similarity index 100%
rename from bin/configs/other/cpp-pistache-server-cpp-pistache.yaml
rename to bin/configs/cpp-pistache-server-cpp-pistache.yaml
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java
index bf49fd425e05..3064af52c20d 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java
@@ -128,6 +128,7 @@ public CppPistacheServerCodegen() {
         typeMapping.put("boolean", "bool");
         typeMapping.put("array", "std::vector");
         typeMapping.put("map", "std::map");
+        typeMapping.put("set", "std::vector");
         typeMapping.put("file", "std::string");
         typeMapping.put("object", "Object");
         typeMapping.put("binary", "std::string");
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-header.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-header.mustache
index 7beb0990a960..f614d478e96c 100644
--- a/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-header.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-header.mustache
@@ -14,24 +14,21 @@
 #include <pistache/http_headers.h>
 #include <pistache/optional.h>
 {{^hasModelImport}}#include <nlohmann/json.hpp>{{/hasModelImport}}
+#include <utility>
 
 {{#imports}}{{{import}}}
 {{/imports}}
 
-{{#apiNamespaceDeclarations}}
-namespace {{this}} {
-{{/apiNamespaceDeclarations}}
-
-{{#hasModelImport}}
-using namespace {{modelNamespace}};{{/hasModelImport}}
+namespace {{apiNamespace}}
+{
 
 class {{declspec}} {{classname}} {
 public:
-    {{classname}}(std::shared_ptr<Pistache::Rest::Router>);
-    virtual ~{{classname}}() {}
+    explicit {{classname}}(const std::shared_ptr<Pistache::Rest::Router>& rtr);
+    virtual ~{{classname}}() = default;
     void init();
 
-    const std::string base = "{{basePathWithoutHost}}";
+    static const std::string base;
 
 private:
     void setupRoutes();
@@ -41,9 +38,21 @@ private:
     {{/operation}}
     void {{classnameSnakeLowerCase}}_default_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response);
 
-    std::shared_ptr<Pistache::Rest::Router> router;
-    {{#operation}}
+    const std::shared_ptr<Pistache::Rest::Router> router;
+
+    /// <summary>
+    /// Helper function to handle unexpected Exceptions during Parameter parsing and validation.
+    /// May be overriden to return custom error formats.
+    /// </summary>
+    virtual std::pair<Pistache::Http::Code, std::string> handleParsingException(const std::exception& ex) const noexcept;
 
+    /// <summary>
+    /// Helper function to handle unexpected Exceptions during processing of the request in handler functions.
+    /// May be overriden to return custom error formats.
+    /// </summary>
+    virtual std::pair<Pistache::Http::Code, std::string> handleOperationException(const std::exception& ex) const noexcept;
+
+    {{#operation}}
     /// <summary>
     /// {{summary}}
     /// </summary>
@@ -54,7 +63,7 @@ private:
     {{#allParams}}
     /// <param name="{{paramName}}">{{description}}{{^required}} (optional{{#defaultValue}}, default to {{.}}{{/defaultValue}}){{/required}}</param>
     {{/allParams}}
-    virtual void {{operationIdSnakeCase}}({{#allParams}}const {{{dataType}}} &{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#hasParams}}, {{/hasParams}}Pistache::Http::ResponseWriter &response) = 0;
+    virtual void {{operationIdSnakeCase}}({{#allParams}}const {{#isModel}}{{modelNamespace}}::{{/isModel}}{{{dataType}}} &{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#hasParams}}, {{/hasParams}}Pistache::Http::ResponseWriter &response) = 0;
     {{/vendorExtensions.x-codegen-pistache-is-parsing-supported}}
     {{^vendorExtensions.x-codegen-pistache-is-parsing-supported}}
     virtual void {{operationIdSnakeCase}}(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter &response) = 0;
@@ -63,9 +72,7 @@ private:
 
 };
 
-{{#apiNamespaceDeclarations}}
-}
-{{/apiNamespaceDeclarations}}
+} // namespace {{apiNamespace}}
 
 #endif /* {{classname}}_H_ */
 
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-impl-header.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-impl-header.mustache
index 18ff119ae208..bd20c1bdf5ab 100644
--- a/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-impl-header.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-impl-header.mustache
@@ -22,17 +22,16 @@
 {{#imports}}{{{import}}}
 {{/imports}}
 
-{{#apiNamespaceDeclarations}}
-namespace {{this}} {
-{{/apiNamespaceDeclarations}}
+namespace {{apiNamespace}}
+{
 
 {{#hasModelImport}}
 using namespace {{modelNamespace}};{{/hasModelImport}}
 
 class {{classname}}Impl : public {{apiNamespace}}::{{classname}} {
 public:
-    {{classname}}Impl(std::shared_ptr<Pistache::Rest::Router>);
-    ~{{classname}}Impl() {}
+    explicit {{classname}}Impl(const std::shared_ptr<Pistache::Rest::Router>& rtr);
+    ~{{classname}}Impl() override = default;
 
     {{#operation}}
     {{#vendorExtensions.x-codegen-pistache-is-parsing-supported}}
@@ -45,11 +44,9 @@ public:
 
 };
 
-{{#apiNamespaceDeclarations}}
-}
-{{/apiNamespaceDeclarations}}
+} // namespace {{apiNamespace}}
 
 {{/operations}}
 
 
-#endif
\ No newline at end of file
+#endif
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-impl-source.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-impl-source.mustache
index e5517bb487c1..2e25a8034b30 100644
--- a/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-impl-source.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-impl-source.mustache
@@ -10,9 +10,10 @@ namespace {{this}} {
 {{#hasModelImport}}
 using namespace {{modelNamespace}};{{/hasModelImport}}
 
-{{classname}}Impl::{{classname}}Impl(std::shared_ptr<Pistache::Rest::Router> rtr)
+{{classname}}Impl::{{classname}}Impl(const std::shared_ptr<Pistache::Rest::Router>& rtr)
     : {{classname}}(rtr)
-    { }
+{
+}
 
 {{#operation}}
 {{#vendorExtensions.x-codegen-pistache-is-parsing-supported}}
@@ -31,4 +32,4 @@ void {{classname}}Impl::{{operationIdSnakeCase}}(const Pistache::Rest::Request &
 }
 {{/apiNamespaceDeclarations}}
 
-{{/operations}}
\ No newline at end of file
+{{/operations}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-source.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-source.mustache
index 9225a5610c70..9814ba0cd626 100644
--- a/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-source.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/api-source.mustache
@@ -4,16 +4,18 @@
 #include "{{classname}}.h"
 #include "{{prefix}}Helpers.h"
 
-{{#apiNamespaceDeclarations}}
-namespace {{this}} {
-{{/apiNamespaceDeclarations}}
+namespace {{apiNamespace}}
+{
 
 using namespace {{helpersNamespace}};
 {{#hasModelImport}}
 using namespace {{modelNamespace}};{{/hasModelImport}}
 
-{{classname}}::{{classname}}(std::shared_ptr<Pistache::Rest::Router> rtr) { 
-    router = rtr;
+const std::string {{classname}}::base = "{{basePathWithoutHost}}";
+
+{{classname}}::{{classname}}(const std::shared_ptr<Pistache::Rest::Router>& rtr)
+    : router(rtr)
+{
 }
 
 void {{classname}}::init() {
@@ -31,8 +33,26 @@ void {{classname}}::setupRoutes() {
     router->addCustomHandler(Routes::bind(&{{classname}}::{{classnameSnakeLowerCase}}_default_handler, this));
 }
 
+std::pair<Pistache::Http::Code, std::string> {{classname}}::handleParsingException(const std::exception& ex) const noexcept
+{
+    try {
+        throw ex;
+    } catch (nlohmann::detail::exception &e) {
+        return std::make_pair(Pistache::Http::Code::Bad_Request, e.what());
+    } catch ({{helpersNamespace}}::ValidationException &e) {
+        return std::make_pair(Pistache::Http::Code::Bad_Request, e.what());
+    }
+}
+
+std::pair<Pistache::Http::Code, std::string> {{classname}}::handleOperationException(const std::exception& ex) const noexcept
+{
+    return std::make_pair(Pistache::Http::Code::Internal_Server_Error, ex.what());
+}
+
 {{#operation}}
 void {{classname}}::{{operationIdSnakeCase}}_handler(const Pistache::Rest::Request &{{#hasParams}}request{{/hasParams}}, Pistache::Http::ResponseWriter response) {
+    try {
+
     {{#vendorExtensions.x-codegen-pistache-is-parsing-supported}}
     {{#hasPathParams}}
     // Getting the path params
@@ -71,32 +91,40 @@ void {{classname}}::{{operationIdSnakeCase}}_handler(const Pistache::Rest::Reque
     {{#hasBodyParam}}
     {{#bodyParam}}
     {{^isPrimitiveType}}
-      nlohmann::json::parse(request.body()).get_to({{paramName}});
+        nlohmann::json::parse(request.body()).get_to({{paramName}});
+        {{paramName}}.validate();
     {{/isPrimitiveType}}
     {{#isPrimitiveType}}
-      {{paramName}} = request.body();
+        {{paramName}} = request.body();
     {{/isPrimitiveType}}
+    } catch (std::exception &e) {
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleParsingException(e);
+        response.send(errorInfo.first, errorInfo.second);
+        return;
+    }
+
+    try {
     {{/bodyParam}}
     {{/hasBodyParam}}
-      this->{{operationIdSnakeCase}}({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#hasParams}}, {{/hasParams}}response);
+        this->{{operationIdSnakeCase}}({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#hasParams}}, {{/hasParams}}response);
     {{/vendorExtensions.x-codegen-pistache-is-parsing-supported}}
     {{^vendorExtensions.x-codegen-pistache-is-parsing-supported}}
     try {
       this->{{operationIdSnakeCase}}(request, response);
     {{/vendorExtensions.x-codegen-pistache-is-parsing-supported}}
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 {{/operation}}
 
@@ -104,8 +132,6 @@ void {{classname}}::{{classnameSnakeLowerCase}}_default_handler(const Pistache::
     response.send(Pistache::Http::Code::Not_Found, "The requested method does not exist");
 }
 
-{{#apiNamespaceDeclarations}}
-}
-{{/apiNamespaceDeclarations}}
+} // namespace {{apiNamespace}}
 
 {{/operations}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/helpers-header.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/helpers-header.mustache
index c39cca04fe10..d3489fad4026 100644
--- a/modules/openapi-generator/src/main/resources/cpp-pistache-server/helpers-header.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/helpers-header.mustache
@@ -14,16 +14,80 @@
 #include <vector>
 #include <map>
 
-{{#helpersNamespaceDeclarations}}
-namespace {{this}} {
-{{/helpersNamespaceDeclarations}}
+namespace {{helpersNamespace}}
+{
+
+    class ValidationException : public std::runtime_error
+    {
+    public:
+        explicit ValidationException(const std::string& what)
+            : std::runtime_error(what)
+        { }
+        ~ValidationException() override = default;
+    };
+
+    /// <summary>
+    /// Validate a string against the full-date definition of RFC 3339, section 5.6.
+    /// </summary>
+    bool validateRfc3339_date(const std::string& str);
+
+    /// <summary>
+    /// Validate a string against the date-time definition of RFC 3339, section 5.6.
+    /// </summary>
+    bool validateRfc3339_date_time(const std::string& str);
+
+    namespace sfinae_helpers
+    {
+        struct NoType {};
+        template <typename T1, typename T2> NoType operator==(const T1&, const T2&);
+
+        template <typename T1, typename T2> class EqualsOperatorAvailable
+        {
+        public:
+            enum
+            {
+                value = !std::is_same< decltype(std::declval<T1>() == std::declval<T2>()), NoType >::value
+            };
+        };
+    } // namespace sfinae_helpers
+
+
+    /// <summary>
+    /// Determine if the given vector<T> only has unique elements. T must provide the == operator.
+    /// </summary>
+    template <typename T>
+    bool hasOnlyUniqueItems(const std::vector<T>& vec)
+    {
+        static_assert(sfinae_helpers::EqualsOperatorAvailable<T, T>::value,
+                      "hasOnlyUniqueItems<T> cannot be called, passed template type does not provide == operator.");
+        if (vec.size() <= 1)
+        {
+            return true;
+        }
+        // Compare every element of vec to every other element of vec.
+        // This isn't an elegant way to do this, since it's O(n^2),
+        // but it's the best solution working only with the == operator.
+        // This could be greatly improved if our models provided a valid hash
+        // and/or the < operator
+        for (size_t i = 0; i < vec.size() - 1; i++)
+        {
+            for (size_t j = i + 1; j < vec.size(); j++)
+            {
+                if (vec[i] == vec[j])
+                {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
 
     std::string toStringValue(const std::string &value);
-    std::string toStringValue(const int32_t &value);
-    std::string toStringValue(const int64_t &value);
-    std::string toStringValue(const bool &value);
-    std::string toStringValue(const float &value);
-    std::string toStringValue(const double &value);
+    std::string toStringValue(const int32_t value);
+    std::string toStringValue(const int64_t value);
+    std::string toStringValue(const bool value);
+    std::string toStringValue(const float value);
+    std::string toStringValue(const double value);
 
     bool fromStringValue(const std::string &inStr, std::string &value);
     bool fromStringValue(const std::string &inStr, int32_t &value);
@@ -57,8 +121,6 @@ namespace {{this}} {
         return fromStringValue(inStrings, value);
     }
 
-{{#helpersNamespaceDeclarations}}
-}
-{{/helpersNamespaceDeclarations}}
+} // namespace {{helpersNamespace}}
 
-#endif // {{prefix}}Helpers_H_
\ No newline at end of file
+#endif // {{prefix}}Helpers_H_
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/helpers-source.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/helpers-source.mustache
index 82b4e2d81ef6..214086354d51 100644
--- a/modules/openapi-generator/src/main/resources/cpp-pistache-server/helpers-source.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/helpers-source.mustache
@@ -1,32 +1,74 @@
 {{>licenseInfo}}
 #include "{{prefix}}Helpers.h"
+#include <regex>
 
-{{#helpersNamespaceDeclarations}}
-namespace {{this}} {
-{{/helpersNamespaceDeclarations}}
+namespace {{helpersNamespace}}
+{
 
+const std::regex regexRfc3339_date(R"(^(\d{4})\-(\d{2})\-(\d{2})$)");
+const std::regex regexRfc3339_date_time(
+    R"(^(\d{4})\-(\d{2})\-(\d{2})[Tt](\d{2}):(\d{2}):(\d{2})(\.\d+)?([Zz]|([\+\-])(\d{2}):(\d{2}))$)"
+);
+
+
+namespace 
+{
+    // Determine if given year is a leap year
+    // See RFC 3339, Appendix C https://tools.ietf.org/html/rfc3339#appendix-C
+    bool isLeapYear(const uint16_t year) {
+        return (year % 4 == 0) && ((year % 100 != 0) || (year % 400 == 0));
+    }
+
+    bool validateDateValues(const uint16_t year, const uint16_t month, const uint16_t day) {
+        return !(
+            (month == 0 || month > 12)
+            || (day == 0)
+            || (month == 2 && day > (28 + (isLeapYear(year) ? 1 : 0)))
+            || (month <= 7 && day > (30 + month % 2))
+            || (month >= 8 && day > (31 - month % 2))
+        );
+    }
+
+    bool validateTimeValues(const uint16_t hours, const uint16_t minutes, const uint16_t seconds) {
+        return (hours <= 23) && (minutes <= 59) && (seconds <= 60);
+    }
+}
+
+bool validateRfc3339_date(const std::string& str) {
+    std::smatch match;
+    const bool found = std::regex_search(str, match, regexRfc3339_date);
+    return found && validateDateValues(std::stoi(match[1]), std::stoi(match[2]), std::stoi(match[3]));
+}
+
+bool validateRfc3339_date_time(const std::string& str) {
+    std::smatch match;
+    const bool found = std::regex_search(str, match, regexRfc3339_date_time);
+    return found
+        && validateDateValues(std::stoi(match[1]), std::stoi(match[2]), std::stoi(match[3]))
+        && validateTimeValues(std::stoi(match[4]), std::stoi(match[5]), std::stoi(match[6]));
+}
 
 std::string toStringValue(const std::string &value){
     return std::string(value);
 }
 
-std::string toStringValue(const int32_t &value){
+std::string toStringValue(const int32_t value){
     return std::to_string(value);
 }
 
-std::string toStringValue(const int64_t &value){
+std::string toStringValue(const int64_t value){
     return std::to_string(value);
 }
 
-std::string toStringValue(const bool &value){
-    return value?std::string("true"):std::string("false");
+std::string toStringValue(const bool value){
+    return value ? std::string("true") : std::string("false");
 }
 
-std::string toStringValue(const float &value){
+std::string toStringValue(const float value){
     return std::to_string(value);
 }
 
-std::string toStringValue(const double &value){
+std::string toStringValue(const double value){
     return std::to_string(value);
 }
 
@@ -56,9 +98,15 @@ bool fromStringValue(const std::string &inStr, int64_t &value){
 }
 
 bool fromStringValue(const std::string &inStr, bool &value){
-    bool result = true;
-    inStr == "true"?value = true: inStr == "false"?value = false: result = false;
-    return result;
+    if (inStr == "true") {
+        value = true;
+        return true;
+    }
+    if (inStr == "false") {
+        value = false;
+        return true;
+    }
+    return false;
 }
 
 bool fromStringValue(const std::string &inStr, float &value){
@@ -81,6 +129,4 @@ bool fromStringValue(const std::string &inStr, double &value){
     return true;
 }
 
-{{#helpersNamespaceDeclarations}}
-}
-{{/helpersNamespaceDeclarations}}
\ No newline at end of file
+} // namespace {{helpersNamespace}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-header.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-header.mustache
index c16fdbb09467..cb6d8d98ee06 100644
--- a/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-header.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-header.mustache
@@ -13,9 +13,8 @@
 {{/imports}}
 #include <nlohmann/json.hpp>
 
-{{#modelNamespaceDeclarations}}
-namespace {{this}} {
-{{/modelNamespaceDeclarations}}
+namespace {{modelNamespace}}
+{
 
 /// <summary>
 /// {{description}}
@@ -24,7 +23,7 @@ class {{declspec}} {{classname}}
 {
 public:
     {{classname}}();
-    virtual ~{{classname}}();
+    virtual ~{{classname}}() = default;
 {{#isEnum}}{{#allowableValues}}
     enum class e{{classname}} {
     // To have a valid default value.
@@ -35,7 +34,20 @@ public:
     {{{name}}}{{^-last}}, {{/-last}}
     {{/enumVars}}
     };{{/allowableValues}}{{/isEnum}}
-    void validate();
+
+    /// <summary>
+    /// Validate the current data in the model. Throws a ValidationException on failure.
+    /// </summary>
+    void validate() const;
+
+    /// <summary>
+    /// Validate the current data in the model. Returns false on error and writes an error
+    /// message into the given stringstream.
+    /// </summary>
+    bool validate(std::stringstream& msg) const;
+
+    bool operator==(const {{classname}}& rhs) const;
+    bool operator!=(const {{classname}}& rhs) const;
 
     /////////////////////////////////////////////
     /// {{classname}} members
@@ -44,7 +56,7 @@ public:
     /// <summary>
     /// {{description}}
     /// </summary>
-    {{{dataType}}}{{#isContainer}}&{{/isContainer}} {{getter}}(){{^isContainer}} const{{/isContainer}};
+    {{{dataType}}} {{getter}}() const;
     void {{setter}}({{{dataType}}} const{{^isPrimitiveType}}&{{/isPrimitiveType}} value);{{^required}}
     bool {{nameInCamelCase}}IsSet() const;
     void unset{{name}}();{{/required}}
@@ -65,11 +77,12 @@ protected:
     {{#isEnum}}
     {{classname}}::e{{classname}} m_value = {{classname}}::e{{classname}}::INVALID_VALUE_OPENAPI_GENERATED;
     {{/isEnum}}
+
+    // Helper overload for validate. Used when one model stores another model and calls it's validate.
+    bool validate(std::stringstream& msg, const std::string& pathPrefix) const;
 };
 
-{{#modelNamespaceDeclarations}}
-}
-{{/modelNamespaceDeclarations}}
+} // namespace {{modelNamespace}}
 
 #endif /* {{classname}}_H_ */
 {{/model}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-source.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-source.mustache
index d603dc2186e0..8ef6abf0e4c5 100644
--- a/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-source.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-source.mustache
@@ -2,12 +2,12 @@
 {{#models}}{{#model}}
 
 #include "{{classname}}.h"
-{{#isEnum}}#include <stdexcept>
-#include <sstream>{{/isEnum}}
+#include "{{prefix}}Helpers.h"
+{{#isEnum}}#include <stdexcept>{{/isEnum}}
+#include <sstream>
 
-{{#modelNamespaceDeclarations}}
-namespace {{this}} {
-{{/modelNamespaceDeclarations}}
+namespace {{modelNamespace}}
+{
 
 {{classname}}::{{classname}}()
 {
@@ -18,13 +18,69 @@ namespace {{this}} {
     {{/required}}{{/vars}}
 }
 
-{{classname}}::~{{classname}}()
+void {{classname}}::validate() const
 {
+    std::stringstream msg;
+    if (!validate(msg))
+    {
+        throw {{helpersNamespace}}::ValidationException(msg.str());
+    }
 }
 
-void {{classname}}::validate()
+bool {{classname}}::validate(std::stringstream& msg) const
 {
-    // TODO: implement validation
+    return validate(msg, "");
+}
+
+bool {{classname}}::validate(std::stringstream& msg, const std::string& pathPrefix) const
+{
+    bool success = true;
+    const std::string _pathPrefix = pathPrefix.empty() ? "{{classname}}" : pathPrefix;
+
+    {{#isEnum}}{{! Special case for enum types }}
+    if (m_value == {{classname}}::e{{classname}}::INVALID_VALUE_OPENAPI_GENERATED)
+    {
+        success = false;
+        msg << _pathPrefix << ": has no value;";
+    }
+    {{/isEnum}}
+    {{^isEnum}}
+    {{#vars}}
+    {{#isArray}} {{! Always generate validation body for array types }}
+    {{^required}}if ({{nameInCamelCase}}IsSet()){{/required}}
+    {{#required}}/* {{name}} */ {{/required}}{
+        const {{{dataType}}}& value = m_{{name}};
+        const std::string currentValuePath = _pathPrefix + ".{{nameInCamelCase}}";
+        {{> model-validation-body }}
+    }
+    {{/isArray}}{{^isArray}}{{#hasValidation}} {{! Only generate validation if necessary }}
+    {{^required}}if ({{nameInCamelCase}}IsSet()){{/required}}
+    {{#required}}/* {{name}} */ {{/required}}{
+        const {{{dataType}}}& value = m_{{name}};
+        const std::string currentValuePath = _pathPrefix + ".{{nameInCamelCase}}";
+        {{> model-validation-body }}
+    }
+    {{/hasValidation}}{{/isArray}}
+    {{/vars}}
+    {{/isEnum}}
+
+    return success;
+}
+
+bool {{classname}}::operator==(const {{classname}}& rhs) const
+{
+    return
+    {{#isEnum}}getValue() == rhs.getValue(){{/isEnum}}
+    {{^isEnum}}{{#vars}}
+    {{#required}}({{getter}}() == rhs.{{getter}}()){{/required}}
+    {{^required}}((!{{nameInCamelCase}}IsSet() && !rhs.{{nameInCamelCase}}IsSet()) || ({{nameInCamelCase}}IsSet() && rhs.{{nameInCamelCase}}IsSet() && {{getter}}() == rhs.{{getter}}())){{/required}}{{^-last}} &&{{/-last}}
+    {{/vars}}{{/isEnum}}
+    ;
+}
+
+bool {{classname}}::operator!=(const {{classname}}& rhs) const
+{
+    return !(*this == rhs);
 }
 
 void to_json(nlohmann::json& j, const {{classname}}& o)
@@ -74,7 +130,7 @@ void from_json(const nlohmann::json& j, {{classname}}& o)
 {{/enumVars}}{{/allowableValues}}{{/isEnum}}
 }
 
-{{#vars}}{{{dataType}}}{{#isContainer}}&{{/isContainer}} {{classname}}::{{getter}}(){{^isContainer}} const{{/isContainer}}
+{{#vars}}{{{dataType}}} {{classname}}::{{getter}}() const
 {
     return m_{{name}};
 }
@@ -102,9 +158,7 @@ void {{classname}}::setValue({{classname}}::e{{classname}} value)
     m_value = value;
 }{{/isEnum}}
 
-{{#modelNamespaceDeclarations}}
-}
-{{/modelNamespaceDeclarations}}
+} // namespace {{modelNamespace}}
 
 {{/model}}
 {{/models}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-struct-header.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-struct-header.mustache
index bcc64257e409..be0ea874da8e 100644
--- a/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-struct-header.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-struct-header.mustache
@@ -14,9 +14,8 @@
 #include <nlohmann/json.hpp>
 {{#hasOptional}}#include <pistache/optional.h>{{/hasOptional}}
 
-{{#modelNamespaceDeclarations}}
-namespace {{this}} {
-{{/modelNamespaceDeclarations}}
+namespace {{modelNamespace}}
+{
 
 struct {{classname}}
 {
@@ -34,9 +33,9 @@ struct {{classname}}
 void to_json(nlohmann::json& j, const {{classname}}& o);
 void from_json(const nlohmann::json& j, {{classname}}& o);
 
-{{#modelNamespaceDeclarations}}
-} // {{this}}
-{{/modelNamespaceDeclarations}}
+
+} // namespace {{modelNamespace}}
+
 
 #endif /* {{classname}}_H_ */
 {{/model}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-struct-source.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-struct-source.mustache
index 52d3526e867a..987926b7c4eb 100644
--- a/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-struct-source.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-struct-source.mustache
@@ -3,9 +3,8 @@
 
 #include "{{classname}}.h"
 
-{{#modelNamespaceDeclarations}}
-namespace {{this}} {
-{{/modelNamespaceDeclarations}}
+namespace {{modelNamespace}}
+{
 
 nlohmann::json {{classname}}::to_json() const
 {
@@ -51,9 +50,7 @@ void from_json(const nlohmann::json& j, {{classname}}& o)
     {{/vars}}
 }
 
-{{#modelNamespaceDeclarations}}
-} // {{this}}
-{{/modelNamespaceDeclarations}}
+} // namespace {{modelNamespace}}
 
 {{/model}}
 {{/models}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-validation-body.mustache b/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-validation-body.mustache
new file mode 100644
index 000000000000..ef92f2c3fbd4
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/cpp-pistache-server/model-validation-body.mustache
@@ -0,0 +1,124 @@
+{{!
+This template generates the validation logic for a model.
+This template file calls itself recursively for arrays.
+}}
+{{! Check for eunm properties that are their own schema }}
+{{! These are in their own class with a validate function, the way to check for this is quite a hack
+since isEnum, isString and isModel are all false. }}
+        {{^isString}}{{#allowableValues.enumVars.0.value}}
+        success = value.validate(msg, currentValuePath) && success;
+        {{/allowableValues.enumVars.0.value}}{{/isString}}
+        {{#isModel}}success = value.validate(msg, currentValuePath + ".{{nameInCamelCase}}") && success;{{/isModel}}
+{{! Date validation }}
+        {{#isDate}}
+        if (!{{helpersNamespace}}::validateRfc3339_date(value))
+        {
+            success = false;
+            msg << currentValuePath << ": must be a valid RFC 3339 date-full string;";
+        }
+        {{/isDate}}
+{{! Date-Time validation }}
+        {{#isDateTime}}
+        if (!{{helpersNamespace}}::validateRfc3339_date_time(value))
+        {
+            success = false;
+            msg << currentValuePath << ": must be a valid RFC 3339 date-time string;";
+        }
+        {{/isDateTime}}
+{{! string validation }}
+        {{#isString}}
+        {{#minLength}}
+        if (value.length() < {{minLength}})
+        {
+            success = false;
+            msg << currentValuePath << ": must be at least {{minLength}} characters long;";
+        }
+        {{/minLength}}
+        {{#maxLength}}
+        if (value.length() > {{maxLength}})
+        {
+            success = false;
+            msg << currentValuePath << ": must be at most {{maxLength}} characters long;";
+        }
+        {{/maxLength}}
+{{!
+TODO validate regex of string using pattern variable. This has two challenges
+    - Is compatibility with the given regex pattern guaranteed?
+    - Creating the std::regex on every validation would be rather slow. Ideally one would
+    initialize them for the class once as a static const and use them.
+}}
+{{! string encoded enum validation }}
+        {{#isEnum}}
+        {{#allowableValues}}
+        if ({{#enumVars}}
+            value != "{{value}}"{{^-last}} &&{{/-last}}{{/enumVars}}
+        ) {
+            success = false;
+            msg << currentValuePath << ": has invalid value \"" << value << "\";";
+        }
+        {{/allowableValues}}
+        {{/isEnum}}
+        {{/isString}}
+{{! numeric validation }}
+        {{#isNumeric}}
+        {{#minimum}}
+        if (value <{{#exclusiveMinimum}}={{/exclusiveMinimum}} {{#isFloat}}static_cast<float>({{/isFloat}}{{minimum}}{{#isFloat}}){{/isFloat}}{{#isLong}}ll{{/isLong}})
+        {
+            success = false;
+            msg << currentValuePath << ": must be greater than{{^exclusiveMinimum}} or equal to{{/exclusiveMinimum}} {{minimum}};";
+        }
+        {{/minimum}}
+        {{#maximum}}
+        if (value >{{#exclusiveMaximum}}={{/exclusiveMaximum}} {{#isFloat}}static_cast<float>({{/isFloat}}{{maximum}}{{#isFloat}}){{/isFloat}}{{#isLong}}ll{{/isLong}})
+        {
+            success = false;
+            msg << currentValuePath << ": must be less than{{^exclusiveMaximum}} or equal to{{/exclusiveMaximum}} {{maximum}};";
+        }
+        {{/maximum}}
+        {{#multipleOf}}
+        {{#isInteger}}if (value % {{multipleOf}}{{#isLong}}ll{{/isLong}} != 0){{/isInteger}}
+        {{#isFloat}}if (std::fmod(value, static_cast<float>({{multipleOf}})) != 0){{/isFloat}}
+        {{#isDouble}}if (std::fmod(value, {{multipleOf}}) != 0){{/isDouble}}
+        {
+            success = false;
+            msg << currentValuePath << ": must be a multiple of {{multipleOf}};";
+        }
+        {{/multipleOf}}
+        {{/isNumeric}}
+{{! Array validation }}
+        {{#isArray}}
+        {{#minItems}}
+        if (value.size() < {{minItems}})
+        {
+            success = false;
+            msg << currentValuePath << ": must have at least {{minItems}} elements;";
+        }
+        {{/minItems}}
+        {{#maxItems}}
+        if (value.size() > {{maxItems}})
+        {
+            success = false;
+            msg << currentValuePath << ": must have at most {{maxItems}} elements;";
+        }
+        {{/maxItems}}
+        {{#uniqueItems}}
+        if (!{{helpersNamespace}}::hasOnlyUniqueItems(value))
+        {
+            success = false;
+            msg << currentValuePath << ": may not contain the same item more than once;";
+        }
+        {{/uniqueItems}}
+        { // Recursive validation of array elements
+            const std::string oldValuePath = currentValuePath;
+            int i = 0;
+            {{! the element var has the same name as the vector, so that the recursive template works - what a wonderful hack }}
+            for (const {{{items.dataType}}}& value : value)
+            { {{! and I do a similar hack with currentValuePath... }}
+                const std::string currentValuePath = oldValuePath + "[" + std::to_string(i) + "]";
+                {{#items}}
+                {{> model-validation-body }} {{! Recursively apply template to array - this is where things will probbaly go wrong }}
+                {{/items}}
+                i++;
+            }
+        }
+        {{/isArray}}
diff --git a/samples/server/petstore/cpp-pistache/.openapi-generator/VERSION b/samples/server/petstore/cpp-pistache/.openapi-generator/VERSION
index c30f0ec2be7f..d509cc92aa80 100644
--- a/samples/server/petstore/cpp-pistache/.openapi-generator/VERSION
+++ b/samples/server/petstore/cpp-pistache/.openapi-generator/VERSION
@@ -1 +1 @@
-5.1.0-SNAPSHOT
\ No newline at end of file
+5.1.1-SNAPSHOT
\ No newline at end of file
diff --git a/samples/server/petstore/cpp-pistache/api/PetApi.cpp b/samples/server/petstore/cpp-pistache/api/PetApi.cpp
index 80e15bd68625..7b3641599eef 100644
--- a/samples/server/petstore/cpp-pistache/api/PetApi.cpp
+++ b/samples/server/petstore/cpp-pistache/api/PetApi.cpp
@@ -13,16 +13,17 @@
 #include "PetApi.h"
 #include "Helpers.h"
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace api {
+namespace org::openapitools::server::api
+{
 
 using namespace org::openapitools::server::helpers;
 using namespace org::openapitools::server::model;
 
-PetApi::PetApi(std::shared_ptr<Pistache::Rest::Router> rtr) { 
-    router = rtr;
+const std::string PetApi::base = "/v2";
+
+PetApi::PetApi(const std::shared_ptr<Pistache::Rest::Router>& rtr)
+    : router(rtr)
+{
 }
 
 void PetApi::init() {
@@ -45,30 +46,58 @@ void PetApi::setupRoutes() {
     router->addCustomHandler(Routes::bind(&PetApi::pet_api_default_handler, this));
 }
 
+std::pair<Pistache::Http::Code, std::string> PetApi::handleParsingException(const std::exception& ex) const noexcept
+{
+    try {
+        throw ex;
+    } catch (nlohmann::detail::exception &e) {
+        return std::make_pair(Pistache::Http::Code::Bad_Request, e.what());
+    } catch (org::openapitools::server::helpers::ValidationException &e) {
+        return std::make_pair(Pistache::Http::Code::Bad_Request, e.what());
+    }
+}
+
+std::pair<Pistache::Http::Code, std::string> PetApi::handleOperationException(const std::exception& ex) const noexcept
+{
+    return std::make_pair(Pistache::Http::Code::Internal_Server_Error, ex.what());
+}
+
 void PetApi::add_pet_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     // Getting the body param
     
     Pet body;
     
     try {
-      nlohmann::json::parse(request.body()).get_to(body);
-      this->add_pet(body, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
+        nlohmann::json::parse(request.body()).get_to(body);
+        body.validate();
+    } catch (std::exception &e) {
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleParsingException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
+    }
+
+    try {
+        this->add_pet(body, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void PetApi::delete_pet_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
     // Getting the path params
     auto petId = request.param(":petId").as<int64_t>();
     
@@ -76,22 +105,24 @@ void PetApi::delete_pet_handler(const Pistache::Rest::Request &request, Pistache
     auto apiKey = request.headers().tryGetRaw("api_key");
 
     try {
-      this->delete_pet(petId, apiKey, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->delete_pet(petId, apiKey, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void PetApi::find_pets_by_status_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     // Getting the query params
     auto statusQuery = request.query().get("status");
@@ -104,22 +135,24 @@ void PetApi::find_pets_by_status_handler(const Pistache::Rest::Request &request,
     }
     
     try {
-      this->find_pets_by_status(status, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->find_pets_by_status(status, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void PetApi::find_pets_by_tags_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     // Getting the query params
     auto tagsQuery = request.query().get("tags");
@@ -132,105 +165,118 @@ void PetApi::find_pets_by_tags_handler(const Pistache::Rest::Request &request, P
     }
     
     try {
-      this->find_pets_by_tags(tags, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->find_pets_by_tags(tags, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void PetApi::get_pet_by_id_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
     // Getting the path params
     auto petId = request.param(":petId").as<int64_t>();
     
     try {
-      this->get_pet_by_id(petId, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->get_pet_by_id(petId, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void PetApi::update_pet_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     // Getting the body param
     
     Pet body;
     
     try {
-      nlohmann::json::parse(request.body()).get_to(body);
-      this->update_pet(body, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
+        nlohmann::json::parse(request.body()).get_to(body);
+        body.validate();
+    } catch (std::exception &e) {
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleParsingException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
+    }
+
+    try {
+        this->update_pet(body, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void PetApi::update_pet_with_form_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
     try {
       this->update_pet_with_form(request, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void PetApi::upload_file_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
     try {
       this->upload_file(request, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 
 void PetApi::pet_api_default_handler(const Pistache::Rest::Request &, Pistache::Http::ResponseWriter response) {
     response.send(Pistache::Http::Code::Not_Found, "The requested method does not exist");
 }
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::api
 
diff --git a/samples/server/petstore/cpp-pistache/api/PetApi.h b/samples/server/petstore/cpp-pistache/api/PetApi.h
index d991d13abaed..f689a0675e15 100644
--- a/samples/server/petstore/cpp-pistache/api/PetApi.h
+++ b/samples/server/petstore/cpp-pistache/api/PetApi.h
@@ -24,25 +24,22 @@
 #include <pistache/http_headers.h>
 #include <pistache/optional.h>
 
+#include <utility>
 
 #include "ApiResponse.h"
 #include "Pet.h"
 #include <string>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace api {
-
-using namespace org::openapitools::server::model;
+namespace org::openapitools::server::api
+{
 
 class  PetApi {
 public:
-    PetApi(std::shared_ptr<Pistache::Rest::Router>);
-    virtual ~PetApi() {}
+    explicit PetApi(const std::shared_ptr<Pistache::Rest::Router>& rtr);
+    virtual ~PetApi() = default;
     void init();
 
-    const std::string base = "/v2";
+    static const std::string base;
 
 private:
     void setupRoutes();
@@ -57,7 +54,19 @@ class  PetApi {
     void upload_file_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response);
     void pet_api_default_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response);
 
-    std::shared_ptr<Pistache::Rest::Router> router;
+    const std::shared_ptr<Pistache::Rest::Router> router;
+
+    /// <summary>
+    /// Helper function to handle unexpected Exceptions during Parameter parsing and validation.
+    /// May be overriden to return custom error formats.
+    /// </summary>
+    virtual std::pair<Pistache::Http::Code, std::string> handleParsingException(const std::exception& ex) const noexcept;
+
+    /// <summary>
+    /// Helper function to handle unexpected Exceptions during processing of the request in handler functions.
+    /// May be overriden to return custom error formats.
+    /// </summary>
+    virtual std::pair<Pistache::Http::Code, std::string> handleOperationException(const std::exception& ex) const noexcept;
 
     /// <summary>
     /// Add a new pet to the store
@@ -66,8 +75,7 @@ class  PetApi {
     /// 
     /// </remarks>
     /// <param name="body">Pet object that needs to be added to the store</param>
-    virtual void add_pet(const Pet &body, Pistache::Http::ResponseWriter &response) = 0;
-
+    virtual void add_pet(const org::openapitools::server::model::Pet &body, Pistache::Http::ResponseWriter &response) = 0;
     /// <summary>
     /// Deletes a pet
     /// </summary>
@@ -77,7 +85,6 @@ class  PetApi {
     /// <param name="petId">Pet id to delete</param>
     /// <param name="apiKey"> (optional, default to &quot;&quot;)</param>
     virtual void delete_pet(const int64_t &petId, const Pistache::Optional<Pistache::Http::Header::Raw> &apiKey, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Finds Pets by status
     /// </summary>
@@ -86,7 +93,6 @@ class  PetApi {
     /// </remarks>
     /// <param name="status">Status values that need to be considered for filter</param>
     virtual void find_pets_by_status(const Pistache::Optional<std::vector<std::string>> &status, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Finds Pets by tags
     /// </summary>
@@ -95,7 +101,6 @@ class  PetApi {
     /// </remarks>
     /// <param name="tags">Tags to filter by</param>
     virtual void find_pets_by_tags(const Pistache::Optional<std::vector<std::string>> &tags, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Find pet by ID
     /// </summary>
@@ -104,7 +109,6 @@ class  PetApi {
     /// </remarks>
     /// <param name="petId">ID of pet to return</param>
     virtual void get_pet_by_id(const int64_t &petId, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Update an existing pet
     /// </summary>
@@ -112,8 +116,7 @@ class  PetApi {
     /// 
     /// </remarks>
     /// <param name="body">Pet object that needs to be added to the store</param>
-    virtual void update_pet(const Pet &body, Pistache::Http::ResponseWriter &response) = 0;
-
+    virtual void update_pet(const org::openapitools::server::model::Pet &body, Pistache::Http::ResponseWriter &response) = 0;
     /// <summary>
     /// Updates a pet in the store with form data
     /// </summary>
@@ -121,7 +124,6 @@ class  PetApi {
     /// 
     /// </remarks>
     virtual void update_pet_with_form(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// uploads an image
     /// </summary>
@@ -132,10 +134,7 @@ class  PetApi {
 
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::api
 
 #endif /* PetApi_H_ */
 
diff --git a/samples/server/petstore/cpp-pistache/api/StoreApi.cpp b/samples/server/petstore/cpp-pistache/api/StoreApi.cpp
index e3f1038f80a4..ea0c0e1793b8 100644
--- a/samples/server/petstore/cpp-pistache/api/StoreApi.cpp
+++ b/samples/server/petstore/cpp-pistache/api/StoreApi.cpp
@@ -13,16 +13,17 @@
 #include "StoreApi.h"
 #include "Helpers.h"
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace api {
+namespace org::openapitools::server::api
+{
 
 using namespace org::openapitools::server::helpers;
 using namespace org::openapitools::server::model;
 
-StoreApi::StoreApi(std::shared_ptr<Pistache::Rest::Router> rtr) { 
-    router = rtr;
+const std::string StoreApi::base = "/v2";
+
+StoreApi::StoreApi(const std::shared_ptr<Pistache::Rest::Router>& rtr)
+    : router(rtr)
+{
 }
 
 void StoreApi::init() {
@@ -41,94 +42,123 @@ void StoreApi::setupRoutes() {
     router->addCustomHandler(Routes::bind(&StoreApi::store_api_default_handler, this));
 }
 
+std::pair<Pistache::Http::Code, std::string> StoreApi::handleParsingException(const std::exception& ex) const noexcept
+{
+    try {
+        throw ex;
+    } catch (nlohmann::detail::exception &e) {
+        return std::make_pair(Pistache::Http::Code::Bad_Request, e.what());
+    } catch (org::openapitools::server::helpers::ValidationException &e) {
+        return std::make_pair(Pistache::Http::Code::Bad_Request, e.what());
+    }
+}
+
+std::pair<Pistache::Http::Code, std::string> StoreApi::handleOperationException(const std::exception& ex) const noexcept
+{
+    return std::make_pair(Pistache::Http::Code::Internal_Server_Error, ex.what());
+}
+
 void StoreApi::delete_order_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
     // Getting the path params
     auto orderId = request.param(":orderId").as<std::string>();
     
     try {
-      this->delete_order(orderId, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->delete_order(orderId, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void StoreApi::get_inventory_handler(const Pistache::Rest::Request &, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     try {
-      this->get_inventory(response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->get_inventory(response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void StoreApi::get_order_by_id_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
     // Getting the path params
     auto orderId = request.param(":orderId").as<int64_t>();
     
     try {
-      this->get_order_by_id(orderId, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->get_order_by_id(orderId, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void StoreApi::place_order_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     // Getting the body param
     
     Order body;
     
     try {
-      nlohmann::json::parse(request.body()).get_to(body);
-      this->place_order(body, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
+        nlohmann::json::parse(request.body()).get_to(body);
+        body.validate();
+    } catch (std::exception &e) {
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleParsingException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
+    }
+
+    try {
+        this->place_order(body, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 
 void StoreApi::store_api_default_handler(const Pistache::Rest::Request &, Pistache::Http::ResponseWriter response) {
     response.send(Pistache::Http::Code::Not_Found, "The requested method does not exist");
 }
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::api
 
diff --git a/samples/server/petstore/cpp-pistache/api/StoreApi.h b/samples/server/petstore/cpp-pistache/api/StoreApi.h
index f69875c4678d..6eb224387479 100644
--- a/samples/server/petstore/cpp-pistache/api/StoreApi.h
+++ b/samples/server/petstore/cpp-pistache/api/StoreApi.h
@@ -24,25 +24,22 @@
 #include <pistache/http_headers.h>
 #include <pistache/optional.h>
 
+#include <utility>
 
 #include "Order.h"
 #include <map>
 #include <string>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace api {
-
-using namespace org::openapitools::server::model;
+namespace org::openapitools::server::api
+{
 
 class  StoreApi {
 public:
-    StoreApi(std::shared_ptr<Pistache::Rest::Router>);
-    virtual ~StoreApi() {}
+    explicit StoreApi(const std::shared_ptr<Pistache::Rest::Router>& rtr);
+    virtual ~StoreApi() = default;
     void init();
 
-    const std::string base = "/v2";
+    static const std::string base;
 
 private:
     void setupRoutes();
@@ -53,7 +50,19 @@ class  StoreApi {
     void place_order_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response);
     void store_api_default_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response);
 
-    std::shared_ptr<Pistache::Rest::Router> router;
+    const std::shared_ptr<Pistache::Rest::Router> router;
+
+    /// <summary>
+    /// Helper function to handle unexpected Exceptions during Parameter parsing and validation.
+    /// May be overriden to return custom error formats.
+    /// </summary>
+    virtual std::pair<Pistache::Http::Code, std::string> handleParsingException(const std::exception& ex) const noexcept;
+
+    /// <summary>
+    /// Helper function to handle unexpected Exceptions during processing of the request in handler functions.
+    /// May be overriden to return custom error formats.
+    /// </summary>
+    virtual std::pair<Pistache::Http::Code, std::string> handleOperationException(const std::exception& ex) const noexcept;
 
     /// <summary>
     /// Delete purchase order by ID
@@ -63,7 +72,6 @@ class  StoreApi {
     /// </remarks>
     /// <param name="orderId">ID of the order that needs to be deleted</param>
     virtual void delete_order(const std::string &orderId, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Returns pet inventories by status
     /// </summary>
@@ -71,7 +79,6 @@ class  StoreApi {
     /// Returns a map of status codes to quantities
     /// </remarks>
     virtual void get_inventory(Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Find purchase order by ID
     /// </summary>
@@ -80,7 +87,6 @@ class  StoreApi {
     /// </remarks>
     /// <param name="orderId">ID of pet that needs to be fetched</param>
     virtual void get_order_by_id(const int64_t &orderId, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Place an order for a pet
     /// </summary>
@@ -88,14 +94,11 @@ class  StoreApi {
     /// 
     /// </remarks>
     /// <param name="body">order placed for purchasing the pet</param>
-    virtual void place_order(const Order &body, Pistache::Http::ResponseWriter &response) = 0;
+    virtual void place_order(const org::openapitools::server::model::Order &body, Pistache::Http::ResponseWriter &response) = 0;
 
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::api
 
 #endif /* StoreApi_H_ */
 
diff --git a/samples/server/petstore/cpp-pistache/api/UserApi.cpp b/samples/server/petstore/cpp-pistache/api/UserApi.cpp
index 93d275611d71..94903581dc4d 100644
--- a/samples/server/petstore/cpp-pistache/api/UserApi.cpp
+++ b/samples/server/petstore/cpp-pistache/api/UserApi.cpp
@@ -13,16 +13,17 @@
 #include "UserApi.h"
 #include "Helpers.h"
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace api {
+namespace org::openapitools::server::api
+{
 
 using namespace org::openapitools::server::helpers;
 using namespace org::openapitools::server::model;
 
-UserApi::UserApi(std::shared_ptr<Pistache::Rest::Router> rtr) { 
-    router = rtr;
+const std::string UserApi::base = "/v2";
+
+UserApi::UserApi(const std::shared_ptr<Pistache::Rest::Router>& rtr)
+    : router(rtr)
+{
 }
 
 void UserApi::init() {
@@ -45,114 +46,166 @@ void UserApi::setupRoutes() {
     router->addCustomHandler(Routes::bind(&UserApi::user_api_default_handler, this));
 }
 
+std::pair<Pistache::Http::Code, std::string> UserApi::handleParsingException(const std::exception& ex) const noexcept
+{
+    try {
+        throw ex;
+    } catch (nlohmann::detail::exception &e) {
+        return std::make_pair(Pistache::Http::Code::Bad_Request, e.what());
+    } catch (org::openapitools::server::helpers::ValidationException &e) {
+        return std::make_pair(Pistache::Http::Code::Bad_Request, e.what());
+    }
+}
+
+std::pair<Pistache::Http::Code, std::string> UserApi::handleOperationException(const std::exception& ex) const noexcept
+{
+    return std::make_pair(Pistache::Http::Code::Internal_Server_Error, ex.what());
+}
+
 void UserApi::create_user_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     // Getting the body param
     
     User body;
     
     try {
-      nlohmann::json::parse(request.body()).get_to(body);
-      this->create_user(body, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
+        nlohmann::json::parse(request.body()).get_to(body);
+        body.validate();
+    } catch (std::exception &e) {
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleParsingException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
+    }
+
+    try {
+        this->create_user(body, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void UserApi::create_users_with_array_input_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     // Getting the body param
     std::vector<User> body;
     
     try {
-      nlohmann::json::parse(request.body()).get_to(body);
-      this->create_users_with_array_input(body, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
+        nlohmann::json::parse(request.body()).get_to(body);
+        body.validate();
+    } catch (std::exception &e) {
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleParsingException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
+    }
+
+    try {
+        this->create_users_with_array_input(body, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void UserApi::create_users_with_list_input_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     // Getting the body param
     std::vector<User> body;
     
     try {
-      nlohmann::json::parse(request.body()).get_to(body);
-      this->create_users_with_list_input(body, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
+        nlohmann::json::parse(request.body()).get_to(body);
+        body.validate();
+    } catch (std::exception &e) {
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleParsingException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
+    }
+
+    try {
+        this->create_users_with_list_input(body, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void UserApi::delete_user_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
     // Getting the path params
     auto username = request.param(":username").as<std::string>();
     
     try {
-      this->delete_user(username, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->delete_user(username, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void UserApi::get_user_by_name_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
     // Getting the path params
     auto username = request.param(":username").as<std::string>();
     
     try {
-      this->get_user_by_name(username, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->get_user_by_name(username, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void UserApi::login_user_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     // Getting the query params
     auto usernameQuery = request.query().get("username");
@@ -173,40 +226,44 @@ void UserApi::login_user_handler(const Pistache::Rest::Request &request, Pistach
     }
     
     try {
-      this->login_user(username, password, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->login_user(username, password, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void UserApi::logout_user_handler(const Pistache::Rest::Request &, Pistache::Http::ResponseWriter response) {
+    try {
+
 
     try {
-      this->logout_user(response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
-        return;
+        this->logout_user(response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 void UserApi::update_user_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response) {
+    try {
+
     // Getting the path params
     auto username = request.param(":username").as<std::string>();
     
@@ -215,29 +272,34 @@ void UserApi::update_user_handler(const Pistache::Rest::Request &request, Pistac
     User body;
     
     try {
-      nlohmann::json::parse(request.body()).get_to(body);
-      this->update_user(username, body, response);
-    } catch (nlohmann::detail::exception &e) {
-        //send a 400 error
-        response.send(Pistache::Http::Code::Bad_Request, e.what());
+        nlohmann::json::parse(request.body()).get_to(body);
+        body.validate();
+    } catch (std::exception &e) {
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleParsingException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
+    }
+
+    try {
+        this->update_user(username, body, response);
     } catch (Pistache::Http::HttpError &e) {
         response.send(static_cast<Pistache::Http::Code>(e.code()), e.what());
         return;
     } catch (std::exception &e) {
-        //send a 500 error
-        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+        const std::pair<Pistache::Http::Code, std::string> errorInfo = this->handleOperationException(e);
+        response.send(errorInfo.first, errorInfo.second);
         return;
     }
 
+    } catch (std::exception &e) {
+        response.send(Pistache::Http::Code::Internal_Server_Error, e.what());
+    }
+
 }
 
 void UserApi::user_api_default_handler(const Pistache::Rest::Request &, Pistache::Http::ResponseWriter response) {
     response.send(Pistache::Http::Code::Not_Found, "The requested method does not exist");
 }
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::api
 
diff --git a/samples/server/petstore/cpp-pistache/api/UserApi.h b/samples/server/petstore/cpp-pistache/api/UserApi.h
index 6c589979dbc9..003b6db4df41 100644
--- a/samples/server/petstore/cpp-pistache/api/UserApi.h
+++ b/samples/server/petstore/cpp-pistache/api/UserApi.h
@@ -24,25 +24,22 @@
 #include <pistache/http_headers.h>
 #include <pistache/optional.h>
 
+#include <utility>
 
 #include "User.h"
 #include <string>
 #include <vector>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace api {
-
-using namespace org::openapitools::server::model;
+namespace org::openapitools::server::api
+{
 
 class  UserApi {
 public:
-    UserApi(std::shared_ptr<Pistache::Rest::Router>);
-    virtual ~UserApi() {}
+    explicit UserApi(const std::shared_ptr<Pistache::Rest::Router>& rtr);
+    virtual ~UserApi() = default;
     void init();
 
-    const std::string base = "/v2";
+    static const std::string base;
 
 private:
     void setupRoutes();
@@ -57,7 +54,19 @@ class  UserApi {
     void update_user_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response);
     void user_api_default_handler(const Pistache::Rest::Request &request, Pistache::Http::ResponseWriter response);
 
-    std::shared_ptr<Pistache::Rest::Router> router;
+    const std::shared_ptr<Pistache::Rest::Router> router;
+
+    /// <summary>
+    /// Helper function to handle unexpected Exceptions during Parameter parsing and validation.
+    /// May be overriden to return custom error formats.
+    /// </summary>
+    virtual std::pair<Pistache::Http::Code, std::string> handleParsingException(const std::exception& ex) const noexcept;
+
+    /// <summary>
+    /// Helper function to handle unexpected Exceptions during processing of the request in handler functions.
+    /// May be overriden to return custom error formats.
+    /// </summary>
+    virtual std::pair<Pistache::Http::Code, std::string> handleOperationException(const std::exception& ex) const noexcept;
 
     /// <summary>
     /// Create user
@@ -66,8 +75,7 @@ class  UserApi {
     /// This can only be done by the logged in user.
     /// </remarks>
     /// <param name="body">Created user object</param>
-    virtual void create_user(const User &body, Pistache::Http::ResponseWriter &response) = 0;
-
+    virtual void create_user(const org::openapitools::server::model::User &body, Pistache::Http::ResponseWriter &response) = 0;
     /// <summary>
     /// Creates list of users with given input array
     /// </summary>
@@ -76,7 +84,6 @@ class  UserApi {
     /// </remarks>
     /// <param name="body">List of user object</param>
     virtual void create_users_with_array_input(const std::vector<User> &body, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Creates list of users with given input array
     /// </summary>
@@ -85,7 +92,6 @@ class  UserApi {
     /// </remarks>
     /// <param name="body">List of user object</param>
     virtual void create_users_with_list_input(const std::vector<User> &body, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Delete user
     /// </summary>
@@ -94,7 +100,6 @@ class  UserApi {
     /// </remarks>
     /// <param name="username">The name that needs to be deleted</param>
     virtual void delete_user(const std::string &username, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Get user by user name
     /// </summary>
@@ -103,7 +108,6 @@ class  UserApi {
     /// </remarks>
     /// <param name="username">The name that needs to be fetched. Use user1 for testing.</param>
     virtual void get_user_by_name(const std::string &username, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Logs user into the system
     /// </summary>
@@ -113,7 +117,6 @@ class  UserApi {
     /// <param name="username">The user name for login</param>
     /// <param name="password">The password for login in clear text</param>
     virtual void login_user(const Pistache::Optional<std::string> &username, const Pistache::Optional<std::string> &password, Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Logs out current logged in user session
     /// </summary>
@@ -121,7 +124,6 @@ class  UserApi {
     /// 
     /// </remarks>
     virtual void logout_user(Pistache::Http::ResponseWriter &response) = 0;
-
     /// <summary>
     /// Updated user
     /// </summary>
@@ -130,14 +132,11 @@ class  UserApi {
     /// </remarks>
     /// <param name="username">name that need to be deleted</param>
     /// <param name="body">Updated user object</param>
-    virtual void update_user(const std::string &username, const User &body, Pistache::Http::ResponseWriter &response) = 0;
+    virtual void update_user(const std::string &username, const org::openapitools::server::model::User &body, Pistache::Http::ResponseWriter &response) = 0;
 
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::api
 
 #endif /* UserApi_H_ */
 
diff --git a/samples/server/petstore/cpp-pistache/impl/PetApiImpl.cpp b/samples/server/petstore/cpp-pistache/impl/PetApiImpl.cpp
index 778117a18bbe..94b49b151e4e 100644
--- a/samples/server/petstore/cpp-pistache/impl/PetApiImpl.cpp
+++ b/samples/server/petstore/cpp-pistache/impl/PetApiImpl.cpp
@@ -19,9 +19,10 @@ namespace api {
 
 using namespace org::openapitools::server::model;
 
-PetApiImpl::PetApiImpl(std::shared_ptr<Pistache::Rest::Router> rtr)
+PetApiImpl::PetApiImpl(const std::shared_ptr<Pistache::Rest::Router>& rtr)
     : PetApi(rtr)
-    { }
+{
+}
 
 void PetApiImpl::add_pet(const Pet &body, Pistache::Http::ResponseWriter &response) {
     response.send(Pistache::Http::Code::Ok, "Do some magic\n");
diff --git a/samples/server/petstore/cpp-pistache/impl/PetApiImpl.h b/samples/server/petstore/cpp-pistache/impl/PetApiImpl.h
index 9e9f3d145baf..82c10b0a410c 100644
--- a/samples/server/petstore/cpp-pistache/impl/PetApiImpl.h
+++ b/samples/server/petstore/cpp-pistache/impl/PetApiImpl.h
@@ -33,17 +33,15 @@
 #include "Pet.h"
 #include <string>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace api {
+namespace org::openapitools::server::api
+{
 
 using namespace org::openapitools::server::model;
 
 class PetApiImpl : public org::openapitools::server::api::PetApi {
 public:
-    PetApiImpl(std::shared_ptr<Pistache::Rest::Router>);
-    ~PetApiImpl() {}
+    explicit PetApiImpl(const std::shared_ptr<Pistache::Rest::Router>& rtr);
+    ~PetApiImpl() override = default;
 
     void add_pet(const Pet &body, Pistache::Http::ResponseWriter &response);
     void delete_pet(const int64_t &petId, const Pistache::Optional<Pistache::Http::Header::Raw> &apiKey, Pistache::Http::ResponseWriter &response);
@@ -56,11 +54,8 @@ class PetApiImpl : public org::openapitools::server::api::PetApi {
 
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::api
 
 
 
-#endif
\ No newline at end of file
+#endif
diff --git a/samples/server/petstore/cpp-pistache/impl/StoreApiImpl.cpp b/samples/server/petstore/cpp-pistache/impl/StoreApiImpl.cpp
index ef164eb0543e..a746316b8039 100644
--- a/samples/server/petstore/cpp-pistache/impl/StoreApiImpl.cpp
+++ b/samples/server/petstore/cpp-pistache/impl/StoreApiImpl.cpp
@@ -19,9 +19,10 @@ namespace api {
 
 using namespace org::openapitools::server::model;
 
-StoreApiImpl::StoreApiImpl(std::shared_ptr<Pistache::Rest::Router> rtr)
+StoreApiImpl::StoreApiImpl(const std::shared_ptr<Pistache::Rest::Router>& rtr)
     : StoreApi(rtr)
-    { }
+{
+}
 
 void StoreApiImpl::delete_order(const std::string &orderId, Pistache::Http::ResponseWriter &response) {
     response.send(Pistache::Http::Code::Ok, "Do some magic\n");
diff --git a/samples/server/petstore/cpp-pistache/impl/StoreApiImpl.h b/samples/server/petstore/cpp-pistache/impl/StoreApiImpl.h
index c99372463184..c5dda64490f7 100644
--- a/samples/server/petstore/cpp-pistache/impl/StoreApiImpl.h
+++ b/samples/server/petstore/cpp-pistache/impl/StoreApiImpl.h
@@ -33,17 +33,15 @@
 #include <map>
 #include <string>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace api {
+namespace org::openapitools::server::api
+{
 
 using namespace org::openapitools::server::model;
 
 class StoreApiImpl : public org::openapitools::server::api::StoreApi {
 public:
-    StoreApiImpl(std::shared_ptr<Pistache::Rest::Router>);
-    ~StoreApiImpl() {}
+    explicit StoreApiImpl(const std::shared_ptr<Pistache::Rest::Router>& rtr);
+    ~StoreApiImpl() override = default;
 
     void delete_order(const std::string &orderId, Pistache::Http::ResponseWriter &response);
     void get_inventory(Pistache::Http::ResponseWriter &response);
@@ -52,11 +50,8 @@ class StoreApiImpl : public org::openapitools::server::api::StoreApi {
 
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::api
 
 
 
-#endif
\ No newline at end of file
+#endif
diff --git a/samples/server/petstore/cpp-pistache/impl/UserApiImpl.cpp b/samples/server/petstore/cpp-pistache/impl/UserApiImpl.cpp
index 7163a560bd77..b477f053c5c8 100644
--- a/samples/server/petstore/cpp-pistache/impl/UserApiImpl.cpp
+++ b/samples/server/petstore/cpp-pistache/impl/UserApiImpl.cpp
@@ -19,9 +19,10 @@ namespace api {
 
 using namespace org::openapitools::server::model;
 
-UserApiImpl::UserApiImpl(std::shared_ptr<Pistache::Rest::Router> rtr)
+UserApiImpl::UserApiImpl(const std::shared_ptr<Pistache::Rest::Router>& rtr)
     : UserApi(rtr)
-    { }
+{
+}
 
 void UserApiImpl::create_user(const User &body, Pistache::Http::ResponseWriter &response) {
     response.send(Pistache::Http::Code::Ok, "Do some magic\n");
diff --git a/samples/server/petstore/cpp-pistache/impl/UserApiImpl.h b/samples/server/petstore/cpp-pistache/impl/UserApiImpl.h
index 8f22c4998894..856a30db5bb1 100644
--- a/samples/server/petstore/cpp-pistache/impl/UserApiImpl.h
+++ b/samples/server/petstore/cpp-pistache/impl/UserApiImpl.h
@@ -33,17 +33,15 @@
 #include <string>
 #include <vector>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace api {
+namespace org::openapitools::server::api
+{
 
 using namespace org::openapitools::server::model;
 
 class UserApiImpl : public org::openapitools::server::api::UserApi {
 public:
-    UserApiImpl(std::shared_ptr<Pistache::Rest::Router>);
-    ~UserApiImpl() {}
+    explicit UserApiImpl(const std::shared_ptr<Pistache::Rest::Router>& rtr);
+    ~UserApiImpl() override = default;
 
     void create_user(const User &body, Pistache::Http::ResponseWriter &response);
     void create_users_with_array_input(const std::vector<User> &body, Pistache::Http::ResponseWriter &response);
@@ -56,11 +54,8 @@ class UserApiImpl : public org::openapitools::server::api::UserApi {
 
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::api
 
 
 
-#endif
\ No newline at end of file
+#endif
diff --git a/samples/server/petstore/cpp-pistache/model/ApiResponse.cpp b/samples/server/petstore/cpp-pistache/model/ApiResponse.cpp
index 4b9ca7419208..049f6c19d6d6 100644
--- a/samples/server/petstore/cpp-pistache/model/ApiResponse.cpp
+++ b/samples/server/petstore/cpp-pistache/model/ApiResponse.cpp
@@ -12,11 +12,12 @@
 
 
 #include "ApiResponse.h"
+#include "Helpers.h"
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+#include <sstream>
+
+namespace org::openapitools::server::model
+{
 
 ApiResponse::ApiResponse()
 {
@@ -29,13 +30,52 @@ ApiResponse::ApiResponse()
     
 }
 
-ApiResponse::~ApiResponse()
+void ApiResponse::validate() const
+{
+    std::stringstream msg;
+    if (!validate(msg))
+    {
+        throw org::openapitools::server::helpers::ValidationException(msg.str());
+    }
+}
+
+bool ApiResponse::validate(std::stringstream& msg) const
+{
+    return validate(msg, "");
+}
+
+bool ApiResponse::validate(std::stringstream& msg, const std::string& pathPrefix) const
+{
+    bool success = true;
+    const std::string _pathPrefix = pathPrefix.empty() ? "ApiResponse" : pathPrefix;
+
+        
+    
+    
+
+    return success;
+}
+
+bool ApiResponse::operator==(const ApiResponse& rhs) const
 {
+    return
+    
+    
+    
+    ((!codeIsSet() && !rhs.codeIsSet()) || (codeIsSet() && rhs.codeIsSet() && getCode() == rhs.getCode())) &&
+    
+    
+    ((!typeIsSet() && !rhs.typeIsSet()) || (typeIsSet() && rhs.typeIsSet() && getType() == rhs.getType())) &&
+    
+    
+    ((!messageIsSet() && !rhs.messageIsSet()) || (messageIsSet() && rhs.messageIsSet() && getMessage() == rhs.getMessage()))
+    
+    ;
 }
 
-void ApiResponse::validate()
+bool ApiResponse::operator!=(const ApiResponse& rhs) const
 {
-    // TODO: implement validation
+    return !(*this == rhs);
 }
 
 void to_json(nlohmann::json& j, const ApiResponse& o)
@@ -123,8 +163,5 @@ void ApiResponse::unsetMessage()
 }
 
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
diff --git a/samples/server/petstore/cpp-pistache/model/ApiResponse.h b/samples/server/petstore/cpp-pistache/model/ApiResponse.h
index 7ecb6c9a82ec..d963b76650bd 100644
--- a/samples/server/petstore/cpp-pistache/model/ApiResponse.h
+++ b/samples/server/petstore/cpp-pistache/model/ApiResponse.h
@@ -22,10 +22,8 @@
 #include <string>
 #include <nlohmann/json.hpp>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+namespace org::openapitools::server::model
+{
 
 /// <summary>
 /// Describes the result of uploading an image resource
@@ -34,9 +32,22 @@ class  ApiResponse
 {
 public:
     ApiResponse();
-    virtual ~ApiResponse();
+    virtual ~ApiResponse() = default;
 
-    void validate();
+
+    /// <summary>
+    /// Validate the current data in the model. Throws a ValidationException on failure.
+    /// </summary>
+    void validate() const;
+
+    /// <summary>
+    /// Validate the current data in the model. Returns false on error and writes an error
+    /// message into the given stringstream.
+    /// </summary>
+    bool validate(std::stringstream& msg) const;
+
+    bool operator==(const ApiResponse& rhs) const;
+    bool operator!=(const ApiResponse& rhs) const;
 
     /////////////////////////////////////////////
     /// ApiResponse members
@@ -72,11 +83,11 @@ class  ApiResponse
     bool m_TypeIsSet;
     std::string m_Message;
     bool m_MessageIsSet;
+
+    // Helper overload for validate. Used when one model stores another model and calls it's validate.
+    bool validate(std::stringstream& msg, const std::string& pathPrefix) const;
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
 #endif /* ApiResponse_H_ */
diff --git a/samples/server/petstore/cpp-pistache/model/Category.cpp b/samples/server/petstore/cpp-pistache/model/Category.cpp
index 3b08114f61de..deb18ff9bb7e 100644
--- a/samples/server/petstore/cpp-pistache/model/Category.cpp
+++ b/samples/server/petstore/cpp-pistache/model/Category.cpp
@@ -12,11 +12,12 @@
 
 
 #include "Category.h"
+#include "Helpers.h"
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+#include <sstream>
+
+namespace org::openapitools::server::model
+{
 
 Category::Category()
 {
@@ -27,13 +28,48 @@ Category::Category()
     
 }
 
-Category::~Category()
+void Category::validate() const
 {
+    std::stringstream msg;
+    if (!validate(msg))
+    {
+        throw org::openapitools::server::helpers::ValidationException(msg.str());
+    }
 }
 
-void Category::validate()
+bool Category::validate(std::stringstream& msg) const
 {
-    // TODO: implement validation
+    return validate(msg, "");
+}
+
+bool Category::validate(std::stringstream& msg, const std::string& pathPrefix) const
+{
+    bool success = true;
+    const std::string _pathPrefix = pathPrefix.empty() ? "Category" : pathPrefix;
+
+        
+    
+
+    return success;
+}
+
+bool Category::operator==(const Category& rhs) const
+{
+    return
+    
+    
+    
+    ((!idIsSet() && !rhs.idIsSet()) || (idIsSet() && rhs.idIsSet() && getId() == rhs.getId())) &&
+    
+    
+    ((!nameIsSet() && !rhs.nameIsSet()) || (nameIsSet() && rhs.nameIsSet() && getName() == rhs.getName()))
+    
+    ;
+}
+
+bool Category::operator!=(const Category& rhs) const
+{
+    return !(*this == rhs);
 }
 
 void to_json(nlohmann::json& j, const Category& o)
@@ -97,8 +133,5 @@ void Category::unsetName()
 }
 
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
diff --git a/samples/server/petstore/cpp-pistache/model/Category.h b/samples/server/petstore/cpp-pistache/model/Category.h
index fa12fdc0de8d..1929ce33e925 100644
--- a/samples/server/petstore/cpp-pistache/model/Category.h
+++ b/samples/server/petstore/cpp-pistache/model/Category.h
@@ -22,10 +22,8 @@
 #include <string>
 #include <nlohmann/json.hpp>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+namespace org::openapitools::server::model
+{
 
 /// <summary>
 /// A category for a pet
@@ -34,9 +32,22 @@ class  Category
 {
 public:
     Category();
-    virtual ~Category();
+    virtual ~Category() = default;
 
-    void validate();
+
+    /// <summary>
+    /// Validate the current data in the model. Throws a ValidationException on failure.
+    /// </summary>
+    void validate() const;
+
+    /// <summary>
+    /// Validate the current data in the model. Returns false on error and writes an error
+    /// message into the given stringstream.
+    /// </summary>
+    bool validate(std::stringstream& msg) const;
+
+    bool operator==(const Category& rhs) const;
+    bool operator!=(const Category& rhs) const;
 
     /////////////////////////////////////////////
     /// Category members
@@ -63,11 +74,11 @@ class  Category
     bool m_IdIsSet;
     std::string m_Name;
     bool m_NameIsSet;
+
+    // Helper overload for validate. Used when one model stores another model and calls it's validate.
+    bool validate(std::stringstream& msg, const std::string& pathPrefix) const;
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
 #endif /* Category_H_ */
diff --git a/samples/server/petstore/cpp-pistache/model/Helpers.cpp b/samples/server/petstore/cpp-pistache/model/Helpers.cpp
index a7774194c82c..cfac2d78986a 100644
--- a/samples/server/petstore/cpp-pistache/model/Helpers.cpp
+++ b/samples/server/petstore/cpp-pistache/model/Helpers.cpp
@@ -10,34 +10,75 @@
 * Do not edit the class manually.
 */
 #include "Helpers.h"
+#include <regex>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace helpers {
+namespace org::openapitools::server::helpers
+{
 
+const std::regex regexRfc3339_date(R"(^(\d{4})\-(\d{2})\-(\d{2})$)");
+const std::regex regexRfc3339_date_time(
+    R"(^(\d{4})\-(\d{2})\-(\d{2})[Tt](\d{2}):(\d{2}):(\d{2})(\.\d+)?([Zz]|([\+\-])(\d{2}):(\d{2}))$)"
+);
+
+
+namespace 
+{
+    // Determine if given year is a leap year
+    // See RFC 3339, Appendix C https://tools.ietf.org/html/rfc3339#appendix-C
+    bool isLeapYear(const uint16_t year) {
+        return (year % 4 == 0) && ((year % 100 != 0) || (year % 400 == 0));
+    }
+
+    bool validateDateValues(const uint16_t year, const uint16_t month, const uint16_t day) {
+        return !(
+            (month == 0 || month > 12)
+            || (day == 0)
+            || (month == 2 && day > (28 + (isLeapYear(year) ? 1 : 0)))
+            || (month <= 7 && day > (30 + month % 2))
+            || (month >= 8 && day > (31 - month % 2))
+        );
+    }
+
+    bool validateTimeValues(const uint16_t hours, const uint16_t minutes, const uint16_t seconds) {
+        return (hours <= 23) && (minutes <= 59) && (seconds <= 60);
+    }
+}
+
+bool validateRfc3339_date(const std::string& str) {
+    std::smatch match;
+    const bool found = std::regex_search(str, match, regexRfc3339_date);
+    return found && validateDateValues(std::stoi(match[1]), std::stoi(match[2]), std::stoi(match[3]));
+}
+
+bool validateRfc3339_date_time(const std::string& str) {
+    std::smatch match;
+    const bool found = std::regex_search(str, match, regexRfc3339_date_time);
+    return found
+        && validateDateValues(std::stoi(match[1]), std::stoi(match[2]), std::stoi(match[3]))
+        && validateTimeValues(std::stoi(match[4]), std::stoi(match[5]), std::stoi(match[6]));
+}
 
 std::string toStringValue(const std::string &value){
     return std::string(value);
 }
 
-std::string toStringValue(const int32_t &value){
+std::string toStringValue(const int32_t value){
     return std::to_string(value);
 }
 
-std::string toStringValue(const int64_t &value){
+std::string toStringValue(const int64_t value){
     return std::to_string(value);
 }
 
-std::string toStringValue(const bool &value){
-    return value?std::string("true"):std::string("false");
+std::string toStringValue(const bool value){
+    return value ? std::string("true") : std::string("false");
 }
 
-std::string toStringValue(const float &value){
+std::string toStringValue(const float value){
     return std::to_string(value);
 }
 
-std::string toStringValue(const double &value){
+std::string toStringValue(const double value){
     return std::to_string(value);
 }
 
@@ -67,9 +108,15 @@ bool fromStringValue(const std::string &inStr, int64_t &value){
 }
 
 bool fromStringValue(const std::string &inStr, bool &value){
-    bool result = true;
-    inStr == "true"?value = true: inStr == "false"?value = false: result = false;
-    return result;
+    if (inStr == "true") {
+        value = true;
+        return true;
+    }
+    if (inStr == "false") {
+        value = false;
+        return true;
+    }
+    return false;
 }
 
 bool fromStringValue(const std::string &inStr, float &value){
@@ -92,7 +139,4 @@ bool fromStringValue(const std::string &inStr, double &value){
     return true;
 }
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::helpers
diff --git a/samples/server/petstore/cpp-pistache/model/Helpers.h b/samples/server/petstore/cpp-pistache/model/Helpers.h
index 9c8c02c4ae61..176b817de1eb 100644
--- a/samples/server/petstore/cpp-pistache/model/Helpers.h
+++ b/samples/server/petstore/cpp-pistache/model/Helpers.h
@@ -24,17 +24,80 @@
 #include <vector>
 #include <map>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace helpers {
+namespace org::openapitools::server::helpers
+{
+
+    class ValidationException : public std::runtime_error
+    {
+    public:
+        explicit ValidationException(const std::string& what)
+            : std::runtime_error(what)
+        { }
+        ~ValidationException() override = default;
+    };
+
+    /// <summary>
+    /// Validate a string against the full-date definition of RFC 3339, section 5.6.
+    /// </summary>
+    bool validateRfc3339_date(const std::string& str);
+
+    /// <summary>
+    /// Validate a string against the date-time definition of RFC 3339, section 5.6.
+    /// </summary>
+    bool validateRfc3339_date_time(const std::string& str);
+
+    namespace sfinae_helpers
+    {
+        struct NoType {};
+        template <typename T1, typename T2> NoType operator==(const T1&, const T2&);
+
+        template <typename T1, typename T2> class EqualsOperatorAvailable
+        {
+        public:
+            enum
+            {
+                value = !std::is_same< decltype(std::declval<T1>() == std::declval<T2>()), NoType >::value
+            };
+        };
+    } // namespace sfinae_helpers
+
+
+    /// <summary>
+    /// Determine if the given vector<T> only has unique elements. T must provide the == operator.
+    /// </summary>
+    template <typename T>
+    bool hasOnlyUniqueItems(const std::vector<T>& vec)
+    {
+        static_assert(sfinae_helpers::EqualsOperatorAvailable<T, T>::value,
+                      "hasOnlyUniqueItems<T> cannot be called, passed template type does not provide == operator.");
+        if (vec.size() <= 1)
+        {
+            return true;
+        }
+        // Compare every element of vec to every other element of vec.
+        // This isn't an elegant way to do this, since it's O(n^2),
+        // but it's the best solution working only with the == operator.
+        // This could be greatly improved if our models provided a valid hash
+        // and/or the < operator
+        for (size_t i = 0; i < vec.size() - 1; i++)
+        {
+            for (size_t j = i + 1; j < vec.size(); j++)
+            {
+                if (vec[i] == vec[j])
+                {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
 
     std::string toStringValue(const std::string &value);
-    std::string toStringValue(const int32_t &value);
-    std::string toStringValue(const int64_t &value);
-    std::string toStringValue(const bool &value);
-    std::string toStringValue(const float &value);
-    std::string toStringValue(const double &value);
+    std::string toStringValue(const int32_t value);
+    std::string toStringValue(const int64_t value);
+    std::string toStringValue(const bool value);
+    std::string toStringValue(const float value);
+    std::string toStringValue(const double value);
 
     bool fromStringValue(const std::string &inStr, std::string &value);
     bool fromStringValue(const std::string &inStr, int32_t &value);
@@ -68,9 +131,6 @@ namespace helpers {
         return fromStringValue(inStrings, value);
     }
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::helpers
 
-#endif // Helpers_H_
\ No newline at end of file
+#endif // Helpers_H_
diff --git a/samples/server/petstore/cpp-pistache/model/Order.cpp b/samples/server/petstore/cpp-pistache/model/Order.cpp
index 986cf6b24fa9..2d04f0ac637b 100644
--- a/samples/server/petstore/cpp-pistache/model/Order.cpp
+++ b/samples/server/petstore/cpp-pistache/model/Order.cpp
@@ -12,11 +12,12 @@
 
 
 #include "Order.h"
+#include "Helpers.h"
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+#include <sstream>
+
+namespace org::openapitools::server::model
+{
 
 Order::Order()
 {
@@ -35,13 +36,64 @@ Order::Order()
     
 }
 
-Order::~Order()
+void Order::validate() const
 {
+    std::stringstream msg;
+    if (!validate(msg))
+    {
+        throw org::openapitools::server::helpers::ValidationException(msg.str());
+    }
 }
 
-void Order::validate()
+bool Order::validate(std::stringstream& msg) const
 {
-    // TODO: implement validation
+    return validate(msg, "");
+}
+
+bool Order::validate(std::stringstream& msg, const std::string& pathPrefix) const
+{
+    bool success = true;
+    const std::string _pathPrefix = pathPrefix.empty() ? "Order" : pathPrefix;
+
+        
+    
+    
+    
+    
+    
+
+    return success;
+}
+
+bool Order::operator==(const Order& rhs) const
+{
+    return
+    
+    
+    
+    ((!idIsSet() && !rhs.idIsSet()) || (idIsSet() && rhs.idIsSet() && getId() == rhs.getId())) &&
+    
+    
+    ((!petIdIsSet() && !rhs.petIdIsSet()) || (petIdIsSet() && rhs.petIdIsSet() && getPetId() == rhs.getPetId())) &&
+    
+    
+    ((!quantityIsSet() && !rhs.quantityIsSet()) || (quantityIsSet() && rhs.quantityIsSet() && getQuantity() == rhs.getQuantity())) &&
+    
+    
+    ((!shipDateIsSet() && !rhs.shipDateIsSet()) || (shipDateIsSet() && rhs.shipDateIsSet() && getShipDate() == rhs.getShipDate())) &&
+    
+    
+    ((!statusIsSet() && !rhs.statusIsSet()) || (statusIsSet() && rhs.statusIsSet() && getStatus() == rhs.getStatus())) &&
+    
+    
+    ((!completeIsSet() && !rhs.completeIsSet()) || (completeIsSet() && rhs.completeIsSet() && isComplete() == rhs.isComplete()))
+    
+    ;
+}
+
+bool Order::operator!=(const Order& rhs) const
+{
+    return !(*this == rhs);
 }
 
 void to_json(nlohmann::json& j, const Order& o)
@@ -201,8 +253,5 @@ void Order::unsetComplete()
 }
 
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
diff --git a/samples/server/petstore/cpp-pistache/model/Order.h b/samples/server/petstore/cpp-pistache/model/Order.h
index d900b633f32c..3d28e1eef6ba 100644
--- a/samples/server/petstore/cpp-pistache/model/Order.h
+++ b/samples/server/petstore/cpp-pistache/model/Order.h
@@ -22,10 +22,8 @@
 #include <string>
 #include <nlohmann/json.hpp>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+namespace org::openapitools::server::model
+{
 
 /// <summary>
 /// An order for a pets from the pet store
@@ -34,9 +32,22 @@ class  Order
 {
 public:
     Order();
-    virtual ~Order();
+    virtual ~Order() = default;
 
-    void validate();
+
+    /// <summary>
+    /// Validate the current data in the model. Throws a ValidationException on failure.
+    /// </summary>
+    void validate() const;
+
+    /// <summary>
+    /// Validate the current data in the model. Returns false on error and writes an error
+    /// message into the given stringstream.
+    /// </summary>
+    bool validate(std::stringstream& msg) const;
+
+    bool operator==(const Order& rhs) const;
+    bool operator!=(const Order& rhs) const;
 
     /////////////////////////////////////////////
     /// Order members
@@ -99,11 +110,11 @@ class  Order
     bool m_StatusIsSet;
     bool m_Complete;
     bool m_CompleteIsSet;
+
+    // Helper overload for validate. Used when one model stores another model and calls it's validate.
+    bool validate(std::stringstream& msg, const std::string& pathPrefix) const;
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
 #endif /* Order_H_ */
diff --git a/samples/server/petstore/cpp-pistache/model/Pet.cpp b/samples/server/petstore/cpp-pistache/model/Pet.cpp
index 434b1339cd06..9c7ba886a44c 100644
--- a/samples/server/petstore/cpp-pistache/model/Pet.cpp
+++ b/samples/server/petstore/cpp-pistache/model/Pet.cpp
@@ -12,11 +12,12 @@
 
 
 #include "Pet.h"
+#include "Helpers.h"
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+#include <sstream>
+
+namespace org::openapitools::server::model
+{
 
 Pet::Pet()
 {
@@ -30,13 +31,106 @@ Pet::Pet()
     
 }
 
-Pet::~Pet()
+void Pet::validate() const
+{
+    std::stringstream msg;
+    if (!validate(msg))
+    {
+        throw org::openapitools::server::helpers::ValidationException(msg.str());
+    }
+}
+
+bool Pet::validate(std::stringstream& msg) const
 {
+    return validate(msg, "");
 }
 
-void Pet::validate()
+bool Pet::validate(std::stringstream& msg, const std::string& pathPrefix) const
 {
-    // TODO: implement validation
+    bool success = true;
+    const std::string _pathPrefix = pathPrefix.empty() ? "Pet" : pathPrefix;
+
+        
+    
+    
+     
+    
+    /* PhotoUrls */ {
+        const std::vector<std::string>& value = m_PhotoUrls;
+        const std::string currentValuePath = _pathPrefix + ".photoUrls";
+                
+        
+        { // Recursive validation of array elements
+            const std::string oldValuePath = currentValuePath;
+            int i = 0;
+            for (const std::string& value : value)
+            { 
+                const std::string currentValuePath = oldValuePath + "[" + std::to_string(i) + "]";
+                        
+        
+ 
+                i++;
+            }
+        }
+
+    }
+    
+     
+    if (tagsIsSet())
+    {
+        const std::vector<Tag>& value = m_Tags;
+        const std::string currentValuePath = _pathPrefix + ".tags";
+                
+        
+        { // Recursive validation of array elements
+            const std::string oldValuePath = currentValuePath;
+            int i = 0;
+            for (const Tag& value : value)
+            { 
+                const std::string currentValuePath = oldValuePath + "[" + std::to_string(i) + "]";
+                        
+        success = value.validate(msg, currentValuePath + ".tags") && success;
+ 
+                i++;
+            }
+        }
+
+    }
+    
+    
+
+    return success;
+}
+
+bool Pet::operator==(const Pet& rhs) const
+{
+    return
+    
+    
+    
+    ((!idIsSet() && !rhs.idIsSet()) || (idIsSet() && rhs.idIsSet() && getId() == rhs.getId())) &&
+    
+    
+    ((!categoryIsSet() && !rhs.categoryIsSet()) || (categoryIsSet() && rhs.categoryIsSet() && getCategory() == rhs.getCategory())) &&
+    
+    (getName() == rhs.getName())
+     &&
+    
+    (getPhotoUrls() == rhs.getPhotoUrls())
+     &&
+    
+    
+    ((!tagsIsSet() && !rhs.tagsIsSet()) || (tagsIsSet() && rhs.tagsIsSet() && getTags() == rhs.getTags())) &&
+    
+    
+    ((!statusIsSet() && !rhs.statusIsSet()) || (statusIsSet() && rhs.statusIsSet() && getStatus() == rhs.getStatus()))
+    
+    ;
+}
+
+bool Pet::operator!=(const Pet& rhs) const
+{
+    return !(*this == rhs);
 }
 
 void to_json(nlohmann::json& j, const Pet& o)
@@ -124,7 +218,7 @@ void Pet::setName(std::string const& value)
 {
     m_Name = value;
 }
-std::vector<std::string>& Pet::getPhotoUrls()
+std::vector<std::string> Pet::getPhotoUrls() const
 {
     return m_PhotoUrls;
 }
@@ -132,7 +226,7 @@ void Pet::setPhotoUrls(std::vector<std::string> const& value)
 {
     m_PhotoUrls = value;
 }
-std::vector<Tag>& Pet::getTags()
+std::vector<Tag> Pet::getTags() const
 {
     return m_Tags;
 }
@@ -168,8 +262,5 @@ void Pet::unsetStatus()
 }
 
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
diff --git a/samples/server/petstore/cpp-pistache/model/Pet.h b/samples/server/petstore/cpp-pistache/model/Pet.h
index eddf475f6ee3..1cd841a08fa7 100644
--- a/samples/server/petstore/cpp-pistache/model/Pet.h
+++ b/samples/server/petstore/cpp-pistache/model/Pet.h
@@ -25,10 +25,8 @@
 #include <vector>
 #include <nlohmann/json.hpp>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+namespace org::openapitools::server::model
+{
 
 /// <summary>
 /// A pet for sale in the pet store
@@ -37,9 +35,22 @@ class  Pet
 {
 public:
     Pet();
-    virtual ~Pet();
+    virtual ~Pet() = default;
 
-    void validate();
+
+    /// <summary>
+    /// Validate the current data in the model. Throws a ValidationException on failure.
+    /// </summary>
+    void validate() const;
+
+    /// <summary>
+    /// Validate the current data in the model. Returns false on error and writes an error
+    /// message into the given stringstream.
+    /// </summary>
+    bool validate(std::stringstream& msg) const;
+
+    bool operator==(const Pet& rhs) const;
+    bool operator!=(const Pet& rhs) const;
 
     /////////////////////////////////////////////
     /// Pet members
@@ -66,12 +77,12 @@ class  Pet
     /// <summary>
     /// 
     /// </summary>
-    std::vector<std::string>& getPhotoUrls();
+    std::vector<std::string> getPhotoUrls() const;
     void setPhotoUrls(std::vector<std::string> const& value);
     /// <summary>
     /// 
     /// </summary>
-    std::vector<Tag>& getTags();
+    std::vector<Tag> getTags() const;
     void setTags(std::vector<Tag> const& value);
     bool tagsIsSet() const;
     void unsetTags();
@@ -98,11 +109,11 @@ class  Pet
     bool m_TagsIsSet;
     std::string m_Status;
     bool m_StatusIsSet;
+
+    // Helper overload for validate. Used when one model stores another model and calls it's validate.
+    bool validate(std::stringstream& msg, const std::string& pathPrefix) const;
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
 #endif /* Pet_H_ */
diff --git a/samples/server/petstore/cpp-pistache/model/Tag.cpp b/samples/server/petstore/cpp-pistache/model/Tag.cpp
index cba759bad1d0..659565e4034d 100644
--- a/samples/server/petstore/cpp-pistache/model/Tag.cpp
+++ b/samples/server/petstore/cpp-pistache/model/Tag.cpp
@@ -12,11 +12,12 @@
 
 
 #include "Tag.h"
+#include "Helpers.h"
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+#include <sstream>
+
+namespace org::openapitools::server::model
+{
 
 Tag::Tag()
 {
@@ -27,13 +28,48 @@ Tag::Tag()
     
 }
 
-Tag::~Tag()
+void Tag::validate() const
 {
+    std::stringstream msg;
+    if (!validate(msg))
+    {
+        throw org::openapitools::server::helpers::ValidationException(msg.str());
+    }
 }
 
-void Tag::validate()
+bool Tag::validate(std::stringstream& msg) const
 {
-    // TODO: implement validation
+    return validate(msg, "");
+}
+
+bool Tag::validate(std::stringstream& msg, const std::string& pathPrefix) const
+{
+    bool success = true;
+    const std::string _pathPrefix = pathPrefix.empty() ? "Tag" : pathPrefix;
+
+        
+    
+
+    return success;
+}
+
+bool Tag::operator==(const Tag& rhs) const
+{
+    return
+    
+    
+    
+    ((!idIsSet() && !rhs.idIsSet()) || (idIsSet() && rhs.idIsSet() && getId() == rhs.getId())) &&
+    
+    
+    ((!nameIsSet() && !rhs.nameIsSet()) || (nameIsSet() && rhs.nameIsSet() && getName() == rhs.getName()))
+    
+    ;
+}
+
+bool Tag::operator!=(const Tag& rhs) const
+{
+    return !(*this == rhs);
 }
 
 void to_json(nlohmann::json& j, const Tag& o)
@@ -97,8 +133,5 @@ void Tag::unsetName()
 }
 
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
diff --git a/samples/server/petstore/cpp-pistache/model/Tag.h b/samples/server/petstore/cpp-pistache/model/Tag.h
index 4b422931d771..ddebeadae431 100644
--- a/samples/server/petstore/cpp-pistache/model/Tag.h
+++ b/samples/server/petstore/cpp-pistache/model/Tag.h
@@ -22,10 +22,8 @@
 #include <string>
 #include <nlohmann/json.hpp>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+namespace org::openapitools::server::model
+{
 
 /// <summary>
 /// A tag for a pet
@@ -34,9 +32,22 @@ class  Tag
 {
 public:
     Tag();
-    virtual ~Tag();
+    virtual ~Tag() = default;
 
-    void validate();
+
+    /// <summary>
+    /// Validate the current data in the model. Throws a ValidationException on failure.
+    /// </summary>
+    void validate() const;
+
+    /// <summary>
+    /// Validate the current data in the model. Returns false on error and writes an error
+    /// message into the given stringstream.
+    /// </summary>
+    bool validate(std::stringstream& msg) const;
+
+    bool operator==(const Tag& rhs) const;
+    bool operator!=(const Tag& rhs) const;
 
     /////////////////////////////////////////////
     /// Tag members
@@ -63,11 +74,11 @@ class  Tag
     bool m_IdIsSet;
     std::string m_Name;
     bool m_NameIsSet;
+
+    // Helper overload for validate. Used when one model stores another model and calls it's validate.
+    bool validate(std::stringstream& msg, const std::string& pathPrefix) const;
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
 #endif /* Tag_H_ */
diff --git a/samples/server/petstore/cpp-pistache/model/User.cpp b/samples/server/petstore/cpp-pistache/model/User.cpp
index 2db9316b75d9..c997bf9734db 100644
--- a/samples/server/petstore/cpp-pistache/model/User.cpp
+++ b/samples/server/petstore/cpp-pistache/model/User.cpp
@@ -12,11 +12,12 @@
 
 
 #include "User.h"
+#include "Helpers.h"
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+#include <sstream>
+
+namespace org::openapitools::server::model
+{
 
 User::User()
 {
@@ -39,13 +40,72 @@ User::User()
     
 }
 
-User::~User()
+void User::validate() const
+{
+    std::stringstream msg;
+    if (!validate(msg))
+    {
+        throw org::openapitools::server::helpers::ValidationException(msg.str());
+    }
+}
+
+bool User::validate(std::stringstream& msg) const
 {
+    return validate(msg, "");
 }
 
-void User::validate()
+bool User::validate(std::stringstream& msg, const std::string& pathPrefix) const
 {
-    // TODO: implement validation
+    bool success = true;
+    const std::string _pathPrefix = pathPrefix.empty() ? "User" : pathPrefix;
+
+        
+    
+    
+    
+    
+    
+    
+    
+
+    return success;
+}
+
+bool User::operator==(const User& rhs) const
+{
+    return
+    
+    
+    
+    ((!idIsSet() && !rhs.idIsSet()) || (idIsSet() && rhs.idIsSet() && getId() == rhs.getId())) &&
+    
+    
+    ((!usernameIsSet() && !rhs.usernameIsSet()) || (usernameIsSet() && rhs.usernameIsSet() && getUsername() == rhs.getUsername())) &&
+    
+    
+    ((!firstNameIsSet() && !rhs.firstNameIsSet()) || (firstNameIsSet() && rhs.firstNameIsSet() && getFirstName() == rhs.getFirstName())) &&
+    
+    
+    ((!lastNameIsSet() && !rhs.lastNameIsSet()) || (lastNameIsSet() && rhs.lastNameIsSet() && getLastName() == rhs.getLastName())) &&
+    
+    
+    ((!emailIsSet() && !rhs.emailIsSet()) || (emailIsSet() && rhs.emailIsSet() && getEmail() == rhs.getEmail())) &&
+    
+    
+    ((!passwordIsSet() && !rhs.passwordIsSet()) || (passwordIsSet() && rhs.passwordIsSet() && getPassword() == rhs.getPassword())) &&
+    
+    
+    ((!phoneIsSet() && !rhs.phoneIsSet()) || (phoneIsSet() && rhs.phoneIsSet() && getPhone() == rhs.getPhone())) &&
+    
+    
+    ((!userStatusIsSet() && !rhs.userStatusIsSet()) || (userStatusIsSet() && rhs.userStatusIsSet() && getUserStatus() == rhs.getUserStatus()))
+    
+    ;
+}
+
+bool User::operator!=(const User& rhs) const
+{
+    return !(*this == rhs);
 }
 
 void to_json(nlohmann::json& j, const User& o)
@@ -253,8 +313,5 @@ void User::unsetUserStatus()
 }
 
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
diff --git a/samples/server/petstore/cpp-pistache/model/User.h b/samples/server/petstore/cpp-pistache/model/User.h
index 1f4c17ce6a81..02bd5f4230a8 100644
--- a/samples/server/petstore/cpp-pistache/model/User.h
+++ b/samples/server/petstore/cpp-pistache/model/User.h
@@ -22,10 +22,8 @@
 #include <string>
 #include <nlohmann/json.hpp>
 
-namespace org {
-namespace openapitools {
-namespace server {
-namespace model {
+namespace org::openapitools::server::model
+{
 
 /// <summary>
 /// A User who is purchasing from the pet store
@@ -34,9 +32,22 @@ class  User
 {
 public:
     User();
-    virtual ~User();
+    virtual ~User() = default;
 
-    void validate();
+
+    /// <summary>
+    /// Validate the current data in the model. Throws a ValidationException on failure.
+    /// </summary>
+    void validate() const;
+
+    /// <summary>
+    /// Validate the current data in the model. Returns false on error and writes an error
+    /// message into the given stringstream.
+    /// </summary>
+    bool validate(std::stringstream& msg) const;
+
+    bool operator==(const User& rhs) const;
+    bool operator!=(const User& rhs) const;
 
     /////////////////////////////////////////////
     /// User members
@@ -117,11 +128,11 @@ class  User
     bool m_PhoneIsSet;
     int32_t m_UserStatus;
     bool m_UserStatusIsSet;
+
+    // Helper overload for validate. Used when one model stores another model and calls it's validate.
+    bool validate(std::stringstream& msg, const std::string& pathPrefix) const;
 };
 
-}
-}
-}
-}
+} // namespace org::openapitools::server::model
 
 #endif /* User_H_ */

From ec085713cec7d51a5ee9e17e5fd4899740354efa Mon Sep 17 00:00:00 2001
From: William Cheng <wing328hk@gmail.com>
Date: Thu, 6 May 2021 10:42:46 +0800
Subject: [PATCH 11/18] [Erlang] migrate CI to drone.io (#9406)

* test erlang client, server in drone.io

* rearrange tests, add server folder

* comment out erlang server tests
---
 CI/.drone.yml | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/CI/.drone.yml b/CI/.drone.yml
index 037fb654724c..a4c8c9b0e95e 100644
--- a/CI/.drone.yml
+++ b/CI/.drone.yml
@@ -1,6 +1,5 @@
 kind: pipeline
 name: default
-
 steps:
 # test Java 11 HTTP client
 - name: java11-test
@@ -54,3 +53,10 @@ steps:
   image: haskell:8.6.5
   commands:
   - (cd samples/client/petstore/haskell-http-client/ && stack --install-ghc --no-haddock-deps haddock --fast && stack test --fast)
+# test erlang client and server
+- name: erlang
+  image: erlang:alpine
+  commands:
+  - (cd samples/client/petstore/erlang-client && rebar3 compile)
+  - (cd samples/client/petstore/erlang-proper && rebar3 compile)
+  #- (cd samples/server/petstore/erlang-server && rebar3 compile)

From 45d55f6b73b166e55ed452cd384eb1a790082817 Mon Sep 17 00:00:00 2001
From: matt beary <1661988+hauntingEcho@users.noreply.github.com>
Date: Wed, 5 May 2021 21:46:06 -0500
Subject: [PATCH 12/18] [aspnetcore] Fix incorrect logging messages (#9405)

* fix incorrect aspnetcore logging messages

* address comments from review

cleans up log messages
---
 .../codegen/languages/AspNetCoreServerCodegen.java             | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AspNetCoreServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AspNetCoreServerCodegen.java
index a52fa88609a5..7786ba8b092d 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AspNetCoreServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AspNetCoreServerCodegen.java
@@ -592,6 +592,7 @@ private void setModelClassModifier() {
     private void setBuildTarget() {
         setCliOption(buildTarget);
         if ("library".equals(buildTarget.getOptValue())) {
+            LOGGER.warn("buildTarget is {} so changing default isLibrary to true",  buildTarget.getOptValue());
             isLibrary = true;
             projectSdk = SDK_LIB;
             additionalProperties.put(CLASS_MODIFIER, "abstract");
@@ -636,7 +637,7 @@ private String determineTemplateVersion(String frameworkVersion) {
 
     private void setUseSwashbuckle() {
         if (isLibrary) {
-            LOGGER.warn("buildTarget is " + buildTarget.getOptValue() + " so changing default isLibrary to false ");
+            LOGGER.warn("isLibrary is true so changing default useSwashbuckle to false");
             useSwashbuckle = false;
         } else {
             useSwashbuckle = true;

From 32b2ea3291dc7cf209449155bcf5bd049f488723 Mon Sep 17 00:00:00 2001
From: matt beary <1661988+hauntingEcho@users.noreply.github.com>
Date: Wed, 5 May 2021 22:23:32 -0500
Subject: [PATCH 13/18] Fixes #9398: fix aspnet enum documentation (#9404)

---
 docs/generators/aspnetcore.md                        | 12 ++++++------
 .../codegen/languages/AspNetCoreServerCodegen.java   | 12 ++++++------
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/docs/generators/aspnetcore.md b/docs/generators/aspnetcore.md
index 0a30830099f5..99f0b789bdc3 100644
--- a/docs/generators/aspnetcore.md
+++ b/docs/generators/aspnetcore.md
@@ -7,9 +7,9 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 
 | Option | Description | Values | Default |
 | ------ | ----------- | ------ | ------- |
-|aspnetCoreVersion|ASP.NET Core version: 5.0, 3.1, 3.0, 2.2, 2.1, 2.0 (deprecated)| |3.1|
-|buildTarget|Target to build an application or library| |program|
-|classModifier|Class Modifier for controller classes: Empty string or abstract.| ||
+|aspnetCoreVersion|ASP.NET Core version: 5.0, 3.1, 3.0, 2.2, 2.1, 2.0 (deprecated)|<dl><dt>**2.0**</dt><dd>ASP.NET Core 2.0</dd><dt>**2.1**</dt><dd>ASP.NET Core 2.1</dd><dt>**2.2**</dt><dd>ASP.NET Core 2.2</dd><dt>**3.0**</dt><dd>ASP.NET Core 3.0</dd><dt>**3.1**</dt><dd>ASP.NET Core 3.1</dd><dt>**5.0**</dt><dd>ASP.NET Core 5.0</dd></dl>|3.1|
+|buildTarget|Target to build an application or library|<dl><dt>**program**</dt><dd>Generate code for a standalone server</dd><dt>**library**</dt><dd>Generate code for a server abstract class library</dd></dl>|program|
+|classModifier|Class Modifier for controller classes: Empty string or abstract.|<dl><dt>****</dt><dd>Keep class default with no modifier</dd><dt>**abstract**</dt><dd>Make class abstract</dd></dl>||
 |compatibilityVersion|ASP.Net Core CompatibilityVersion| |Version_2_2|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumValueSuffix|Suffix that will be appended to all enum values.| |Enum|
@@ -17,10 +17,10 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |isLibrary|Is the build a library| |false|
 |licenseName|The name of the license| |NoLicense|
 |licenseUrl|The URL of the license| |http://localhost|
-|modelClassModifier|Model Class Modifier can be nothing or partial| |partial|
+|modelClassModifier|Model Class Modifier can be nothing or partial|<dl><dt>****</dt><dd>Keep model class default with no modifier</dd><dt>**partial**</dt><dd>Make model class partial</dd></dl>|partial|
 |newtonsoftVersion|Version for Microsoft.AspNetCore.Mvc.NewtonsoftJson for ASP.NET Core 3.0+| |3.0.0|
 |operationIsAsync|Set methods to async or sync (default).| |false|
-|operationModifier|Operation Modifier can be virtual or abstract| |virtual|
+|operationModifier|Operation Modifier can be virtual or abstract|<dl><dt>**virtual**</dt><dd>Keep method virtual</dd><dt>**abstract**</dt><dd>Make method abstract</dd></dl>|virtual|
 |operationResultTask|Set methods result to Task&lt;&gt;.| |false|
 |packageAuthors|Specifies Authors property in the .NET Core project file.| |OpenAPI|
 |packageCopyright|Specifies an AssemblyCopyright for the .NET Framework global assembly attributes stored in the AssemblyInfo file.| |No Copyright|
@@ -32,7 +32,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |returnICollection|Return ICollection&lt;T&gt; instead of the concrete type.| |false|
 |sortParamsByRequiredFlag|Sort method arguments to place required parameters before optional parameters.| |true|
 |sourceFolder|source folder for generated code| |src|
-|swashbuckleVersion|Swashbuckle version: 3.0.0, 4.0.0, 5.0.0| |3.0.0|
+|swashbuckleVersion|Swashbuckle version: 3.0.0, 4.0.0, 5.0.0|<dl><dt>**3.0.0**</dt><dd>Swashbuckle 3.0.0</dd><dt>**4.0.0**</dt><dd>Swashbuckle 4.0.0</dd><dt>**5.0.0**</dt><dd>Swashbuckle 5.0.0</dd></dl>|3.0.0|
 |useCollection|Deserialize array types to Collection&lt;T&gt; instead of List&lt;T&gt;.| |false|
 |useDateTimeOffset|Use DateTimeOffset to model date-time properties| |false|
 |useDefaultRouting|Use default routing for the ASP.NET Core version.| |true|
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AspNetCoreServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AspNetCoreServerCodegen.java
index 7786ba8b092d..f7c24196331e 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AspNetCoreServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AspNetCoreServerCodegen.java
@@ -199,14 +199,14 @@ public AspNetCoreServerCodegen() {
         aspnetCoreVersion.addEnum("5.0", "ASP.NET Core 5.0");
         aspnetCoreVersion.setDefault("3.1");
         aspnetCoreVersion.setOptValue(aspnetCoreVersion.getDefault());
-        addOption(aspnetCoreVersion.getOpt(), aspnetCoreVersion.getDescription(), aspnetCoreVersion.getOptValue());
+        cliOptions.add(aspnetCoreVersion);
 
         swashbuckleVersion.addEnum("3.0.0", "Swashbuckle 3.0.0");
         swashbuckleVersion.addEnum("4.0.0", "Swashbuckle 4.0.0");
         swashbuckleVersion.addEnum("5.0.0", "Swashbuckle 5.0.0");
         swashbuckleVersion.setDefault("3.0.0");
         swashbuckleVersion.setOptValue(swashbuckleVersion.getDefault());
-        addOption(swashbuckleVersion.getOpt(), swashbuckleVersion.getDescription(), swashbuckleVersion.getOptValue());
+        cliOptions.add(swashbuckleVersion);
 
         // CLI Switches
         addSwitch(CodegenConstants.SORT_PARAMS_BY_REQUIRED_FLAG,
@@ -261,19 +261,19 @@ public AspNetCoreServerCodegen() {
         classModifier.addEnum("abstract", "Make class abstract");
         classModifier.setDefault("");
         classModifier.setOptValue(classModifier.getDefault());
-        addOption(classModifier.getOpt(), classModifier.getDescription(), classModifier.getOptValue());
+        cliOptions.add(classModifier);
 
         operationModifier.addEnum("virtual", "Keep method virtual");
         operationModifier.addEnum("abstract", "Make method abstract");
         operationModifier.setDefault("virtual");
         operationModifier.setOptValue(operationModifier.getDefault());
-        addOption(operationModifier.getOpt(), operationModifier.getDescription(), operationModifier.getOptValue());
+        cliOptions.add(operationModifier);
 
         buildTarget.addEnum("program", "Generate code for a standalone server");
         buildTarget.addEnum("library", "Generate code for a server abstract class library");
         buildTarget.setDefault("program");
         buildTarget.setOptValue(buildTarget.getDefault());
-        addOption(buildTarget.getOpt(), buildTarget.getDescription(), buildTarget.getOptValue());
+        cliOptions.add(buildTarget);
 
         addSwitch(GENERATE_BODY,
                 "Generates method body.",
@@ -292,7 +292,7 @@ public AspNetCoreServerCodegen() {
         modelClassModifier.addEnum("partial", "Make model class partial");
         modelClassModifier.setDefault("partial");
         modelClassModifier.setOptValue(modelClassModifier.getDefault());
-        addOption(modelClassModifier.getOpt(), modelClassModifier.getDescription(), modelClassModifier.getOptValue());
+        cliOptions.add(modelClassModifier);
     }
 
     @Override

From 343d7eb712159d6dc00a62f8158167398a835f13 Mon Sep 17 00:00:00 2001
From: Samuel Kahn <48932506+Kahncode@users.noreply.github.com>
Date: Thu, 6 May 2021 05:26:07 +0200
Subject: [PATCH 14/18] [cpp-ue4] Improved retry system to use Unreal's
 FHttpRetrySystem (#9382)

* Revert "[cpp-ue4] Added the possibility to retry requests easily with AsyncRetry method on the response and SetAutoRetryCount on the request"

* [cpp-ue4] Improved retry system to use Unreal's FHttpRetrySystem

* [cpp-ue4] Updated style guide link

* update samples

Co-authored-by: William Cheng <wing328hk@gmail.com>
---
 CONTRIBUTING.md                               |   1 +
 .../resources/cpp-ue4/api-header.mustache     |  16 +-
 .../resources/cpp-ue4/api-source.mustache     |  53 +++--
 .../cpp-ue4/model-base-header.mustache        |  40 +++-
 .../cpp-ue4/model-base-source.mustache        |  30 +--
 .../cpp-ue4/Private/OpenAPIBaseModel.cpp      |  30 +--
 .../cpp-ue4/Private/OpenAPIPetApi.cpp         | 186 +++++++-----------
 .../cpp-ue4/Private/OpenAPIStoreApi.cpp       | 110 +++++------
 .../cpp-ue4/Private/OpenAPIUserApi.cpp        | 186 +++++++-----------
 .../cpp-ue4/Public/OpenAPIBaseModel.h         |  40 +++-
 .../petstore/cpp-ue4/Public/OpenAPIPetApi.h   |  30 ++-
 .../petstore/cpp-ue4/Public/OpenAPIStoreApi.h |  22 ++-
 .../petstore/cpp-ue4/Public/OpenAPIUserApi.h  |  30 ++-
 13 files changed, 394 insertions(+), 380 deletions(-)

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 30258ec9fd6c..0fe833163afa 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -48,6 +48,7 @@ Code change should conform to the programming style guide of the respective lang
 - C#: https://msdn.microsoft.com/en-us/library/vstudio/ff926074.aspx
 - C++: https://google.github.io/styleguide/cppguide.html
 - C++ (Tizen): https://wiki.tizen.org/Native_Platform_Coding_Idiom_and_Style_Guide#C.2B.2B_Coding_Style
+- C++ (Unreal Engine 4): https://docs.unrealengine.com/en-US/ProductionPipelines/DevelopmentSetup/CodingStandard/index.html
 - Clojure: https://github.com/bbatsov/clojure-style-guide
 - Crystal: https://crystal-lang.org/reference/conventions/coding_style.html
 - Dart: https://www.dartlang.org/guides/language/effective-dart/style
diff --git a/modules/openapi-generator/src/main/resources/cpp-ue4/api-header.mustache b/modules/openapi-generator/src/main/resources/cpp-ue4/api-header.mustache
index c6ee2f08eb44..17b42e942ea7 100644
--- a/modules/openapi-generator/src/main/resources/cpp-ue4/api-header.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-ue4/api-header.mustache
@@ -15,9 +15,19 @@ public:
 	{{classname}}();
 	~{{classname}}();
 
+	/* Sets the URL Endpoint. 
+	* Note: several fallback endpoints can be configured in request retry policies, see Request::SetShouldRetry */
 	void SetURL(const FString& Url);
+
+	/* Adds global header params to all requests */
 	void AddHeaderParam(const FString& Key, const FString& Value);
 	void ClearHeaderParams();
+	
+	/* Sets the retry manager to the user-defined retry manager. User must manage the lifetime of the retry manager.
+	* If no retry manager is specified and a request needs retries, a default retry manager will be used. 
+	* See also: Request::SetShouldRetry */
+	void SetHttpRetryManager(FHttpRetrySystem::FManager& RetryManager);
+	FHttpRetrySystem::FManager& GetHttpRetryManager();
 
 	{{#operations}}{{#operation}}class {{operationIdCamelCase}}Request;
 	class {{operationIdCamelCase}}Response;
@@ -27,15 +37,17 @@ public:
     {{#operations}}{{#operation}}{{#description}}/* {{{description}}} */
 	{{/description}}bool {{operationIdCamelCase}}(const {{operationIdCamelCase}}Request& Request, const F{{operationIdCamelCase}}Delegate& Delegate = F{{operationIdCamelCase}}Delegate()) const;
     {{/operation}}{{/operations}}
-
 private:
-    {{#operations}}{{#operation}}void On{{operationIdCamelCase}}Response(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, F{{operationIdCamelCase}}Delegate Delegate, int AutoRetryCount) const;
+    {{#operations}}{{#operation}}void On{{operationIdCamelCase}}Response(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, F{{operationIdCamelCase}}Delegate Delegate) const;
     {{/operation}}{{/operations}}
+	FHttpRequestRef CreateHttpRequest(const Request& Request) const;
 	bool IsValid() const;
 	void HandleResponse(FHttpResponsePtr HttpResponse, bool bSucceeded, Response& InOutResponse) const;
 
 	FString Url;
 	TMap<FString,FString> AdditionalHeaderParams;
+	mutable FHttpRetrySystem::FManager* RetryManager = nullptr;
+	mutable TUniquePtr<HttpRetryManager> DefaultRetryManager;
 };
 	
 {{#cppNamespaceDeclarations}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-ue4/api-source.mustache b/modules/openapi-generator/src/main/resources/cpp-ue4/api-source.mustache
index 8a9b38545444..9bd9f3b87bde 100644
--- a/modules/openapi-generator/src/main/resources/cpp-ue4/api-source.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-ue4/api-source.mustache
@@ -45,6 +45,40 @@ bool {{classname}}::IsValid() const
 	return true;
 }
 
+void {{classname}}::SetHttpRetryManager(FHttpRetrySystem::FManager& InRetryManager)
+{
+	if(RetryManager != &GetHttpRetryManager())
+	{
+		DefaultRetryManager.Reset();
+		RetryManager = &InRetryManager;
+	}
+}
+
+FHttpRetrySystem::FManager& {{classname}}::GetHttpRetryManager()
+{
+	return *RetryManager;
+}
+
+FHttpRequestRef {{classname}}::CreateHttpRequest(const Request& Request) const
+{
+	if (!Request.GetRetryParams().IsSet())
+	{
+		return FHttpModule::Get().CreateRequest();
+	}
+	else
+	{
+		if (!RetryManager)
+		{
+			// Create default retry manager if none was specified
+			DefaultRetryManager = MakeUnique<HttpRetryManager>(6, 60);
+			RetryManager = DefaultRetryManager.Get();
+		}
+
+		const HttpRetryParams& Params = Request.GetRetryParams().GetValue();
+		return RetryManager->CreateRequest(Params.RetryLimitCountOverride, Params.RetryTimeoutRelativeSecondsOverride, Params.RetryResponseCodes, Params.RetryVerbs, Params.RetryDomains);
+	}
+}
+
 void {{classname}}::HandleResponse(FHttpResponsePtr HttpResponse, bool bSucceeded, Response& InOutResponse) const
 {
 	InOutResponse.SetHttpResponse(HttpResponse);
@@ -96,7 +130,7 @@ bool {{classname}}::{{operationIdCamelCase}}(const {{operationIdCamelCase}}Reque
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -106,26 +140,15 @@ bool {{classname}}::{{operationIdCamelCase}}(const {{operationIdCamelCase}}Reque
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &{{classname}}::On{{operationIdCamelCase}}Response, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &{{classname}}::On{{operationIdCamelCase}}Response, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void {{classname}}::On{{operationIdCamelCase}}Response(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, F{{operationIdCamelCase}}Delegate Delegate, int AutoRetryCount) const
+void {{classname}}::On{{operationIdCamelCase}}Response(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, F{{operationIdCamelCase}}Delegate Delegate) const
 {
 	{{operationIdCamelCase}}Response Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &{{classname}}::On{{operationIdCamelCase}}Response, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 {{/operation}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-ue4/model-base-header.mustache b/modules/openapi-generator/src/main/resources/cpp-ue4/model-base-header.mustache
index 31b0bdabd260..2f5b6255f54a 100644
--- a/modules/openapi-generator/src/main/resources/cpp-ue4/model-base-header.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-ue4/model-base-header.mustache
@@ -5,6 +5,8 @@
 #include "Interfaces/IHttpResponse.h"
 #include "Serialization/JsonWriter.h"
 #include "Dom/JsonObject.h"
+#include "HttpRetrySystem.h"
+#include "Containers/Ticker.h"
 
 {{#cppNamespaceDeclarations}}
 namespace {{this}} 
@@ -12,6 +14,31 @@ namespace {{this}}
 {{/cppNamespaceDeclarations}}
 
 typedef TSharedRef<TJsonWriter<>> JsonWriter;
+using namespace FHttpRetrySystem;
+
+struct {{dllapi}} HttpRetryManager : public FManager, public FTickerObjectBase
+{
+	using FManager::FManager;
+
+	bool Tick(float DeltaTime) final;
+};
+
+struct {{dllapi}} HttpRetryParams
+{
+	HttpRetryParams(
+		const FRetryLimitCountSetting& InRetryLimitCountOverride = FRetryLimitCountSetting(),
+		const FRetryTimeoutRelativeSecondsSetting& InRetryTimeoutRelativeSecondsOverride = FRetryTimeoutRelativeSecondsSetting(),
+		const FRetryResponseCodes& InRetryResponseCodes = FRetryResponseCodes(),
+		const FRetryVerbs& InRetryVerbs = FRetryVerbs(),
+		const FRetryDomainsPtr& InRetryDomains = FRetryDomainsPtr()
+	);
+
+	FRetryLimitCountSetting              RetryLimitCountOverride;
+	FRetryTimeoutRelativeSecondsSetting  RetryTimeoutRelativeSecondsOverride;
+	FRetryResponseCodes					 RetryResponseCodes;
+	FRetryVerbs                          RetryVerbs;
+	FRetryDomainsPtr					 RetryDomains;
+};
 
 class {{dllapi}} Model
 { 
@@ -28,11 +55,12 @@ public:
 	virtual void SetupHttpRequest(const FHttpRequestRef& HttpRequest) const = 0;
 	virtual FString ComputePath() const = 0;
 
-	void SetAutoRetryCount(int InCount) { AutoRetryCount = InCount; }
-	int GetAutoRetryCount() const { return AutoRetryCount; }
+	/* Enables retry and optionally sets a retry policy for this request */
+	void SetShouldRetry(const HttpRetryParams& Params = HttpRetryParams()) { RetryParams = Params; }
+	const TOptional<HttpRetryParams>& GetRetryParams() const { return RetryParams; }
 
 private:
-	int AutoRetryCount = 0;
+	TOptional<HttpRetryParams> RetryParams;
 };
 
 class {{dllapi}} Response
@@ -44,8 +72,6 @@ public:
 	void SetSuccessful(bool InSuccessful) { Successful = InSuccessful; }
 	bool IsSuccessful() const { return Successful; }
 
-	void AsyncRetry() const;
-
 	virtual void SetHttpResponseCode(EHttpResponseCodes::Type InHttpResponseCode);
 	EHttpResponseCodes::Type GetHttpResponseCode() const { return ResponseCode; }
 
@@ -55,15 +81,11 @@ public:
 	void SetHttpResponse(const FHttpResponsePtr& InHttpResponse) { HttpResponse = InHttpResponse; }
 	const FHttpResponsePtr& GetHttpResponse() const { return HttpResponse; }
 
-	void SetHttpRequest(const FHttpRequestPtr& InHttpRequest) { HttpRequest = InHttpRequest; }
-	const FHttpRequestPtr& GetHttpRequest() const { return HttpRequest; }
-
 private:
 	bool Successful;
 	EHttpResponseCodes::Type ResponseCode;
 	FString ResponseString;
 	FHttpResponsePtr HttpResponse;
-	FHttpRequestPtr HttpRequest;
 };
 
 {{#cppNamespaceDeclarations}}
diff --git a/modules/openapi-generator/src/main/resources/cpp-ue4/model-base-source.mustache b/modules/openapi-generator/src/main/resources/cpp-ue4/model-base-source.mustache
index a5ab70a432f7..57dc4fb4151c 100644
--- a/modules/openapi-generator/src/main/resources/cpp-ue4/model-base-source.mustache
+++ b/modules/openapi-generator/src/main/resources/cpp-ue4/model-base-source.mustache
@@ -1,13 +1,30 @@
 {{>licenseInfo}}
 #include "{{modelNamePrefix}}BaseModel.h"
 
-#include "Async/Async.h"
-
 {{#cppNamespaceDeclarations}}
 namespace {{this}} 
 {
 {{/cppNamespaceDeclarations}}
 
+bool HttpRetryManager::Tick(float DeltaTime)
+{
+	FManager::Update();
+	return true;
+}
+
+HttpRetryParams::HttpRetryParams(const FRetryLimitCountSetting& InRetryLimitCountOverride /*= FRetryLimitCountSetting()*/, 
+    const FRetryTimeoutRelativeSecondsSetting& InRetryTimeoutRelativeSecondsOverride /*= FRetryTimeoutRelativeSecondsSetting()*/, 
+    const FRetryResponseCodes& InRetryResponseCodes /*= FRetryResponseCodes()*/, 
+    const FRetryVerbs& InRetryVerbs /*= FRetryVerbs()*/, 
+    const FRetryDomainsPtr& InRetryDomains /*= FRetryDomainsPtr() */)
+    : RetryLimitCountOverride(InRetryLimitCountOverride)
+    , RetryTimeoutRelativeSecondsOverride(InRetryTimeoutRelativeSecondsOverride)
+    , RetryResponseCodes(InRetryResponseCodes)
+    , RetryVerbs(InRetryVerbs)
+    , RetryDomains(InRetryDomains)
+{
+}
+
 void Response::SetHttpResponseCode(EHttpResponseCodes::Type InHttpResponseCode)
 {
     ResponseCode = InHttpResponseCode;
@@ -18,15 +35,6 @@ void Response::SetHttpResponseCode(EHttpResponseCodes::Type InHttpResponseCode)
     }
 }
 
-void Response::AsyncRetry() const
-{
-    // Unfortunately, it is currently usafe to call ProcessRequest() directly here.
-    // This is because the HttpManager will remove all references to this HttpRequest in FHttpManager::Tick including the new request we just added, instead of removing just one. 
-    // This will lead to the request's destruction and eventually a crash.
-    // The only solution is therefore to ensure we are taking an extra reference to the request, and that the request is added after the queue is flushed.
-    Async(EAsyncExecution::TaskGraph, [AddRef = FHttpRequestPtr(GetHttpRequest())](){ AddRef->ProcessRequest(); });
-}
-
 {{#cppNamespaceDeclarations}}
 }
 {{/cppNamespaceDeclarations}}
\ No newline at end of file
diff --git a/samples/client/petstore/cpp-ue4/Private/OpenAPIBaseModel.cpp b/samples/client/petstore/cpp-ue4/Private/OpenAPIBaseModel.cpp
index b277e2570285..f8552ac0b7d9 100644
--- a/samples/client/petstore/cpp-ue4/Private/OpenAPIBaseModel.cpp
+++ b/samples/client/petstore/cpp-ue4/Private/OpenAPIBaseModel.cpp
@@ -12,11 +12,28 @@
 
 #include "OpenAPIBaseModel.h"
 
-#include "Async/Async.h"
-
 namespace OpenAPI 
 {
 
+bool HttpRetryManager::Tick(float DeltaTime)
+{
+	FManager::Update();
+	return true;
+}
+
+HttpRetryParams::HttpRetryParams(const FRetryLimitCountSetting& InRetryLimitCountOverride /*= FRetryLimitCountSetting()*/, 
+    const FRetryTimeoutRelativeSecondsSetting& InRetryTimeoutRelativeSecondsOverride /*= FRetryTimeoutRelativeSecondsSetting()*/, 
+    const FRetryResponseCodes& InRetryResponseCodes /*= FRetryResponseCodes()*/, 
+    const FRetryVerbs& InRetryVerbs /*= FRetryVerbs()*/, 
+    const FRetryDomainsPtr& InRetryDomains /*= FRetryDomainsPtr() */)
+    : RetryLimitCountOverride(InRetryLimitCountOverride)
+    , RetryTimeoutRelativeSecondsOverride(InRetryTimeoutRelativeSecondsOverride)
+    , RetryResponseCodes(InRetryResponseCodes)
+    , RetryVerbs(InRetryVerbs)
+    , RetryDomains(InRetryDomains)
+{
+}
+
 void Response::SetHttpResponseCode(EHttpResponseCodes::Type InHttpResponseCode)
 {
     ResponseCode = InHttpResponseCode;
@@ -27,13 +44,4 @@ void Response::SetHttpResponseCode(EHttpResponseCodes::Type InHttpResponseCode)
     }
 }
 
-void Response::AsyncRetry() const
-{
-    // Unfortunately, it is currently usafe to call ProcessRequest() directly here.
-    // This is because the HttpManager will remove all references to this HttpRequest in FHttpManager::Tick including the new request we just added, instead of removing just one. 
-    // This will lead to the request's destruction and eventually a crash.
-    // The only solution is therefore to ensure we are taking an extra reference to the request, and that the request is added after the queue is flushed.
-    Async(EAsyncExecution::TaskGraph, [AddRef = FHttpRequestPtr(GetHttpRequest())](){ AddRef->ProcessRequest(); });
-}
-
 }
diff --git a/samples/client/petstore/cpp-ue4/Private/OpenAPIPetApi.cpp b/samples/client/petstore/cpp-ue4/Private/OpenAPIPetApi.cpp
index 68a0d933aca7..72d2c58ea6e1 100644
--- a/samples/client/petstore/cpp-ue4/Private/OpenAPIPetApi.cpp
+++ b/samples/client/petstore/cpp-ue4/Private/OpenAPIPetApi.cpp
@@ -54,6 +54,40 @@ bool OpenAPIPetApi::IsValid() const
 	return true;
 }
 
+void OpenAPIPetApi::SetHttpRetryManager(FHttpRetrySystem::FManager& InRetryManager)
+{
+	if(RetryManager != &GetHttpRetryManager())
+	{
+		DefaultRetryManager.Reset();
+		RetryManager = &InRetryManager;
+	}
+}
+
+FHttpRetrySystem::FManager& OpenAPIPetApi::GetHttpRetryManager()
+{
+	return *RetryManager;
+}
+
+FHttpRequestRef OpenAPIPetApi::CreateHttpRequest(const Request& Request) const
+{
+	if (!Request.GetRetryParams().IsSet())
+	{
+		return FHttpModule::Get().CreateRequest();
+	}
+	else
+	{
+		if (!RetryManager)
+		{
+			// Create default retry manager if none was specified
+			DefaultRetryManager = MakeUnique<HttpRetryManager>(6, 60);
+			RetryManager = DefaultRetryManager.Get();
+		}
+
+		const HttpRetryParams& Params = Request.GetRetryParams().GetValue();
+		return RetryManager->CreateRequest(Params.RetryLimitCountOverride, Params.RetryTimeoutRelativeSecondsOverride, Params.RetryResponseCodes, Params.RetryVerbs, Params.RetryDomains);
+	}
+}
+
 void OpenAPIPetApi::HandleResponse(FHttpResponsePtr HttpResponse, bool bSucceeded, Response& InOutResponse) const
 {
 	InOutResponse.SetHttpResponse(HttpResponse);
@@ -103,7 +137,7 @@ bool OpenAPIPetApi::AddPet(const AddPetRequest& Request, const FAddPetDelegate&
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -113,26 +147,15 @@ bool OpenAPIPetApi::AddPet(const AddPetRequest& Request, const FAddPetDelegate&
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnAddPetResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnAddPetResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIPetApi::OnAddPetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FAddPetDelegate Delegate, int AutoRetryCount) const
+void OpenAPIPetApi::OnAddPetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FAddPetDelegate Delegate) const
 {
 	AddPetResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnAddPetResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIPetApi::DeletePet(const DeletePetRequest& Request, const FDeletePetDelegate& Delegate /*= FDeletePetDelegate()*/) const
@@ -140,7 +163,7 @@ bool OpenAPIPetApi::DeletePet(const DeletePetRequest& Request, const FDeletePetD
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -150,26 +173,15 @@ bool OpenAPIPetApi::DeletePet(const DeletePetRequest& Request, const FDeletePetD
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnDeletePetResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnDeletePetResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIPetApi::OnDeletePetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeletePetDelegate Delegate, int AutoRetryCount) const
+void OpenAPIPetApi::OnDeletePetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeletePetDelegate Delegate) const
 {
 	DeletePetResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnDeletePetResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIPetApi::FindPetsByStatus(const FindPetsByStatusRequest& Request, const FFindPetsByStatusDelegate& Delegate /*= FFindPetsByStatusDelegate()*/) const
@@ -177,7 +189,7 @@ bool OpenAPIPetApi::FindPetsByStatus(const FindPetsByStatusRequest& Request, con
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -187,26 +199,15 @@ bool OpenAPIPetApi::FindPetsByStatus(const FindPetsByStatusRequest& Request, con
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnFindPetsByStatusResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnFindPetsByStatusResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIPetApi::OnFindPetsByStatusResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FFindPetsByStatusDelegate Delegate, int AutoRetryCount) const
+void OpenAPIPetApi::OnFindPetsByStatusResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FFindPetsByStatusDelegate Delegate) const
 {
 	FindPetsByStatusResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnFindPetsByStatusResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIPetApi::FindPetsByTags(const FindPetsByTagsRequest& Request, const FFindPetsByTagsDelegate& Delegate /*= FFindPetsByTagsDelegate()*/) const
@@ -214,7 +215,7 @@ bool OpenAPIPetApi::FindPetsByTags(const FindPetsByTagsRequest& Request, const F
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -224,26 +225,15 @@ bool OpenAPIPetApi::FindPetsByTags(const FindPetsByTagsRequest& Request, const F
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnFindPetsByTagsResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnFindPetsByTagsResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIPetApi::OnFindPetsByTagsResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FFindPetsByTagsDelegate Delegate, int AutoRetryCount) const
+void OpenAPIPetApi::OnFindPetsByTagsResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FFindPetsByTagsDelegate Delegate) const
 {
 	FindPetsByTagsResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnFindPetsByTagsResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIPetApi::GetPetById(const GetPetByIdRequest& Request, const FGetPetByIdDelegate& Delegate /*= FGetPetByIdDelegate()*/) const
@@ -251,7 +241,7 @@ bool OpenAPIPetApi::GetPetById(const GetPetByIdRequest& Request, const FGetPetBy
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -261,26 +251,15 @@ bool OpenAPIPetApi::GetPetById(const GetPetByIdRequest& Request, const FGetPetBy
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnGetPetByIdResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnGetPetByIdResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIPetApi::OnGetPetByIdResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetPetByIdDelegate Delegate, int AutoRetryCount) const
+void OpenAPIPetApi::OnGetPetByIdResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetPetByIdDelegate Delegate) const
 {
 	GetPetByIdResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnGetPetByIdResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIPetApi::UpdatePet(const UpdatePetRequest& Request, const FUpdatePetDelegate& Delegate /*= FUpdatePetDelegate()*/) const
@@ -288,7 +267,7 @@ bool OpenAPIPetApi::UpdatePet(const UpdatePetRequest& Request, const FUpdatePetD
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -298,26 +277,15 @@ bool OpenAPIPetApi::UpdatePet(const UpdatePetRequest& Request, const FUpdatePetD
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnUpdatePetResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnUpdatePetResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIPetApi::OnUpdatePetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdatePetDelegate Delegate, int AutoRetryCount) const
+void OpenAPIPetApi::OnUpdatePetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdatePetDelegate Delegate) const
 {
 	UpdatePetResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnUpdatePetResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIPetApi::UpdatePetWithForm(const UpdatePetWithFormRequest& Request, const FUpdatePetWithFormDelegate& Delegate /*= FUpdatePetWithFormDelegate()*/) const
@@ -325,7 +293,7 @@ bool OpenAPIPetApi::UpdatePetWithForm(const UpdatePetWithFormRequest& Request, c
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -335,26 +303,15 @@ bool OpenAPIPetApi::UpdatePetWithForm(const UpdatePetWithFormRequest& Request, c
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnUpdatePetWithFormResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnUpdatePetWithFormResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIPetApi::OnUpdatePetWithFormResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdatePetWithFormDelegate Delegate, int AutoRetryCount) const
+void OpenAPIPetApi::OnUpdatePetWithFormResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdatePetWithFormDelegate Delegate) const
 {
 	UpdatePetWithFormResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnUpdatePetWithFormResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIPetApi::UploadFile(const UploadFileRequest& Request, const FUploadFileDelegate& Delegate /*= FUploadFileDelegate()*/) const
@@ -362,7 +319,7 @@ bool OpenAPIPetApi::UploadFile(const UploadFileRequest& Request, const FUploadFi
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -372,26 +329,15 @@ bool OpenAPIPetApi::UploadFile(const UploadFileRequest& Request, const FUploadFi
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnUploadFileResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnUploadFileResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIPetApi::OnUploadFileResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUploadFileDelegate Delegate, int AutoRetryCount) const
+void OpenAPIPetApi::OnUploadFileResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUploadFileDelegate Delegate) const
 {
 	UploadFileResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIPetApi::OnUploadFileResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 }
diff --git a/samples/client/petstore/cpp-ue4/Private/OpenAPIStoreApi.cpp b/samples/client/petstore/cpp-ue4/Private/OpenAPIStoreApi.cpp
index 32000a959073..ed25814006e0 100644
--- a/samples/client/petstore/cpp-ue4/Private/OpenAPIStoreApi.cpp
+++ b/samples/client/petstore/cpp-ue4/Private/OpenAPIStoreApi.cpp
@@ -54,6 +54,40 @@ bool OpenAPIStoreApi::IsValid() const
 	return true;
 }
 
+void OpenAPIStoreApi::SetHttpRetryManager(FHttpRetrySystem::FManager& InRetryManager)
+{
+	if(RetryManager != &GetHttpRetryManager())
+	{
+		DefaultRetryManager.Reset();
+		RetryManager = &InRetryManager;
+	}
+}
+
+FHttpRetrySystem::FManager& OpenAPIStoreApi::GetHttpRetryManager()
+{
+	return *RetryManager;
+}
+
+FHttpRequestRef OpenAPIStoreApi::CreateHttpRequest(const Request& Request) const
+{
+	if (!Request.GetRetryParams().IsSet())
+	{
+		return FHttpModule::Get().CreateRequest();
+	}
+	else
+	{
+		if (!RetryManager)
+		{
+			// Create default retry manager if none was specified
+			DefaultRetryManager = MakeUnique<HttpRetryManager>(6, 60);
+			RetryManager = DefaultRetryManager.Get();
+		}
+
+		const HttpRetryParams& Params = Request.GetRetryParams().GetValue();
+		return RetryManager->CreateRequest(Params.RetryLimitCountOverride, Params.RetryTimeoutRelativeSecondsOverride, Params.RetryResponseCodes, Params.RetryVerbs, Params.RetryDomains);
+	}
+}
+
 void OpenAPIStoreApi::HandleResponse(FHttpResponsePtr HttpResponse, bool bSucceeded, Response& InOutResponse) const
 {
 	InOutResponse.SetHttpResponse(HttpResponse);
@@ -103,7 +137,7 @@ bool OpenAPIStoreApi::DeleteOrder(const DeleteOrderRequest& Request, const FDele
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -113,26 +147,15 @@ bool OpenAPIStoreApi::DeleteOrder(const DeleteOrderRequest& Request, const FDele
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnDeleteOrderResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnDeleteOrderResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIStoreApi::OnDeleteOrderResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeleteOrderDelegate Delegate, int AutoRetryCount) const
+void OpenAPIStoreApi::OnDeleteOrderResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeleteOrderDelegate Delegate) const
 {
 	DeleteOrderResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnDeleteOrderResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIStoreApi::GetInventory(const GetInventoryRequest& Request, const FGetInventoryDelegate& Delegate /*= FGetInventoryDelegate()*/) const
@@ -140,7 +163,7 @@ bool OpenAPIStoreApi::GetInventory(const GetInventoryRequest& Request, const FGe
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -150,26 +173,15 @@ bool OpenAPIStoreApi::GetInventory(const GetInventoryRequest& Request, const FGe
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnGetInventoryResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnGetInventoryResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIStoreApi::OnGetInventoryResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetInventoryDelegate Delegate, int AutoRetryCount) const
+void OpenAPIStoreApi::OnGetInventoryResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetInventoryDelegate Delegate) const
 {
 	GetInventoryResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnGetInventoryResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIStoreApi::GetOrderById(const GetOrderByIdRequest& Request, const FGetOrderByIdDelegate& Delegate /*= FGetOrderByIdDelegate()*/) const
@@ -177,7 +189,7 @@ bool OpenAPIStoreApi::GetOrderById(const GetOrderByIdRequest& Request, const FGe
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -187,26 +199,15 @@ bool OpenAPIStoreApi::GetOrderById(const GetOrderByIdRequest& Request, const FGe
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnGetOrderByIdResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnGetOrderByIdResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIStoreApi::OnGetOrderByIdResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetOrderByIdDelegate Delegate, int AutoRetryCount) const
+void OpenAPIStoreApi::OnGetOrderByIdResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetOrderByIdDelegate Delegate) const
 {
 	GetOrderByIdResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnGetOrderByIdResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIStoreApi::PlaceOrder(const PlaceOrderRequest& Request, const FPlaceOrderDelegate& Delegate /*= FPlaceOrderDelegate()*/) const
@@ -214,7 +215,7 @@ bool OpenAPIStoreApi::PlaceOrder(const PlaceOrderRequest& Request, const FPlaceO
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -224,26 +225,15 @@ bool OpenAPIStoreApi::PlaceOrder(const PlaceOrderRequest& Request, const FPlaceO
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnPlaceOrderResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnPlaceOrderResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIStoreApi::OnPlaceOrderResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FPlaceOrderDelegate Delegate, int AutoRetryCount) const
+void OpenAPIStoreApi::OnPlaceOrderResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FPlaceOrderDelegate Delegate) const
 {
 	PlaceOrderResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIStoreApi::OnPlaceOrderResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 }
diff --git a/samples/client/petstore/cpp-ue4/Private/OpenAPIUserApi.cpp b/samples/client/petstore/cpp-ue4/Private/OpenAPIUserApi.cpp
index 9fdd937b3b9e..8f38a6358f46 100644
--- a/samples/client/petstore/cpp-ue4/Private/OpenAPIUserApi.cpp
+++ b/samples/client/petstore/cpp-ue4/Private/OpenAPIUserApi.cpp
@@ -54,6 +54,40 @@ bool OpenAPIUserApi::IsValid() const
 	return true;
 }
 
+void OpenAPIUserApi::SetHttpRetryManager(FHttpRetrySystem::FManager& InRetryManager)
+{
+	if(RetryManager != &GetHttpRetryManager())
+	{
+		DefaultRetryManager.Reset();
+		RetryManager = &InRetryManager;
+	}
+}
+
+FHttpRetrySystem::FManager& OpenAPIUserApi::GetHttpRetryManager()
+{
+	return *RetryManager;
+}
+
+FHttpRequestRef OpenAPIUserApi::CreateHttpRequest(const Request& Request) const
+{
+	if (!Request.GetRetryParams().IsSet())
+	{
+		return FHttpModule::Get().CreateRequest();
+	}
+	else
+	{
+		if (!RetryManager)
+		{
+			// Create default retry manager if none was specified
+			DefaultRetryManager = MakeUnique<HttpRetryManager>(6, 60);
+			RetryManager = DefaultRetryManager.Get();
+		}
+
+		const HttpRetryParams& Params = Request.GetRetryParams().GetValue();
+		return RetryManager->CreateRequest(Params.RetryLimitCountOverride, Params.RetryTimeoutRelativeSecondsOverride, Params.RetryResponseCodes, Params.RetryVerbs, Params.RetryDomains);
+	}
+}
+
 void OpenAPIUserApi::HandleResponse(FHttpResponsePtr HttpResponse, bool bSucceeded, Response& InOutResponse) const
 {
 	InOutResponse.SetHttpResponse(HttpResponse);
@@ -103,7 +137,7 @@ bool OpenAPIUserApi::CreateUser(const CreateUserRequest& Request, const FCreateU
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -113,26 +147,15 @@ bool OpenAPIUserApi::CreateUser(const CreateUserRequest& Request, const FCreateU
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnCreateUserResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnCreateUserResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIUserApi::OnCreateUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUserDelegate Delegate, int AutoRetryCount) const
+void OpenAPIUserApi::OnCreateUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUserDelegate Delegate) const
 {
 	CreateUserResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnCreateUserResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIUserApi::CreateUsersWithArrayInput(const CreateUsersWithArrayInputRequest& Request, const FCreateUsersWithArrayInputDelegate& Delegate /*= FCreateUsersWithArrayInputDelegate()*/) const
@@ -140,7 +163,7 @@ bool OpenAPIUserApi::CreateUsersWithArrayInput(const CreateUsersWithArrayInputRe
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -150,26 +173,15 @@ bool OpenAPIUserApi::CreateUsersWithArrayInput(const CreateUsersWithArrayInputRe
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnCreateUsersWithArrayInputResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnCreateUsersWithArrayInputResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIUserApi::OnCreateUsersWithArrayInputResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUsersWithArrayInputDelegate Delegate, int AutoRetryCount) const
+void OpenAPIUserApi::OnCreateUsersWithArrayInputResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUsersWithArrayInputDelegate Delegate) const
 {
 	CreateUsersWithArrayInputResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnCreateUsersWithArrayInputResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIUserApi::CreateUsersWithListInput(const CreateUsersWithListInputRequest& Request, const FCreateUsersWithListInputDelegate& Delegate /*= FCreateUsersWithListInputDelegate()*/) const
@@ -177,7 +189,7 @@ bool OpenAPIUserApi::CreateUsersWithListInput(const CreateUsersWithListInputRequ
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -187,26 +199,15 @@ bool OpenAPIUserApi::CreateUsersWithListInput(const CreateUsersWithListInputRequ
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnCreateUsersWithListInputResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnCreateUsersWithListInputResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIUserApi::OnCreateUsersWithListInputResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUsersWithListInputDelegate Delegate, int AutoRetryCount) const
+void OpenAPIUserApi::OnCreateUsersWithListInputResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUsersWithListInputDelegate Delegate) const
 {
 	CreateUsersWithListInputResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnCreateUsersWithListInputResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIUserApi::DeleteUser(const DeleteUserRequest& Request, const FDeleteUserDelegate& Delegate /*= FDeleteUserDelegate()*/) const
@@ -214,7 +215,7 @@ bool OpenAPIUserApi::DeleteUser(const DeleteUserRequest& Request, const FDeleteU
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -224,26 +225,15 @@ bool OpenAPIUserApi::DeleteUser(const DeleteUserRequest& Request, const FDeleteU
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnDeleteUserResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnDeleteUserResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIUserApi::OnDeleteUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeleteUserDelegate Delegate, int AutoRetryCount) const
+void OpenAPIUserApi::OnDeleteUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeleteUserDelegate Delegate) const
 {
 	DeleteUserResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnDeleteUserResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIUserApi::GetUserByName(const GetUserByNameRequest& Request, const FGetUserByNameDelegate& Delegate /*= FGetUserByNameDelegate()*/) const
@@ -251,7 +241,7 @@ bool OpenAPIUserApi::GetUserByName(const GetUserByNameRequest& Request, const FG
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -261,26 +251,15 @@ bool OpenAPIUserApi::GetUserByName(const GetUserByNameRequest& Request, const FG
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnGetUserByNameResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnGetUserByNameResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIUserApi::OnGetUserByNameResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetUserByNameDelegate Delegate, int AutoRetryCount) const
+void OpenAPIUserApi::OnGetUserByNameResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetUserByNameDelegate Delegate) const
 {
 	GetUserByNameResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnGetUserByNameResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIUserApi::LoginUser(const LoginUserRequest& Request, const FLoginUserDelegate& Delegate /*= FLoginUserDelegate()*/) const
@@ -288,7 +267,7 @@ bool OpenAPIUserApi::LoginUser(const LoginUserRequest& Request, const FLoginUser
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -298,26 +277,15 @@ bool OpenAPIUserApi::LoginUser(const LoginUserRequest& Request, const FLoginUser
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnLoginUserResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnLoginUserResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIUserApi::OnLoginUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FLoginUserDelegate Delegate, int AutoRetryCount) const
+void OpenAPIUserApi::OnLoginUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FLoginUserDelegate Delegate) const
 {
 	LoginUserResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnLoginUserResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIUserApi::LogoutUser(const LogoutUserRequest& Request, const FLogoutUserDelegate& Delegate /*= FLogoutUserDelegate()*/) const
@@ -325,7 +293,7 @@ bool OpenAPIUserApi::LogoutUser(const LogoutUserRequest& Request, const FLogoutU
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -335,26 +303,15 @@ bool OpenAPIUserApi::LogoutUser(const LogoutUserRequest& Request, const FLogoutU
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnLogoutUserResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnLogoutUserResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIUserApi::OnLogoutUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FLogoutUserDelegate Delegate, int AutoRetryCount) const
+void OpenAPIUserApi::OnLogoutUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FLogoutUserDelegate Delegate) const
 {
 	LogoutUserResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnLogoutUserResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 bool OpenAPIUserApi::UpdateUser(const UpdateUserRequest& Request, const FUpdateUserDelegate& Delegate /*= FUpdateUserDelegate()*/) const
@@ -362,7 +319,7 @@ bool OpenAPIUserApi::UpdateUser(const UpdateUserRequest& Request, const FUpdateU
 	if (!IsValid())
 		return false;
 
-	FHttpRequestRef HttpRequest = FHttpModule::Get().CreateRequest();
+	FHttpRequestRef HttpRequest = CreateHttpRequest(Request);
 	HttpRequest->SetURL(*(Url + Request.ComputePath()));
 
 	for(const auto& It : AdditionalHeaderParams)
@@ -372,26 +329,15 @@ bool OpenAPIUserApi::UpdateUser(const UpdateUserRequest& Request, const FUpdateU
 
 	Request.SetupHttpRequest(HttpRequest);
 	
-	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnUpdateUserResponse, Delegate, Request.GetAutoRetryCount());
+	HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnUpdateUserResponse, Delegate);
 	return HttpRequest->ProcessRequest();
 }
 
-void OpenAPIUserApi::OnUpdateUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdateUserDelegate Delegate, int AutoRetryCount) const
+void OpenAPIUserApi::OnUpdateUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdateUserDelegate Delegate) const
 {
 	UpdateUserResponse Response;
-	Response.SetHttpRequest(HttpRequest);
-
 	HandleResponse(HttpResponse, bSucceeded, Response);
-
-	if(!Response.IsSuccessful() && AutoRetryCount > 0)
-	{
-		HttpRequest->OnProcessRequestComplete().BindRaw(this, &OpenAPIUserApi::OnUpdateUserResponse, Delegate, AutoRetryCount - 1);
-		Response.AsyncRetry();
-	}
-	else
-	{
-		Delegate.ExecuteIfBound(Response);
-	}
+	Delegate.ExecuteIfBound(Response);
 }
 
 }
diff --git a/samples/client/petstore/cpp-ue4/Public/OpenAPIBaseModel.h b/samples/client/petstore/cpp-ue4/Public/OpenAPIBaseModel.h
index d73441e1326c..538589752458 100644
--- a/samples/client/petstore/cpp-ue4/Public/OpenAPIBaseModel.h
+++ b/samples/client/petstore/cpp-ue4/Public/OpenAPIBaseModel.h
@@ -16,11 +16,38 @@
 #include "Interfaces/IHttpResponse.h"
 #include "Serialization/JsonWriter.h"
 #include "Dom/JsonObject.h"
+#include "HttpRetrySystem.h"
+#include "Containers/Ticker.h"
 
 namespace OpenAPI 
 {
 
 typedef TSharedRef<TJsonWriter<>> JsonWriter;
+using namespace FHttpRetrySystem;
+
+struct OPENAPI_API HttpRetryManager : public FManager, public FTickerObjectBase
+{
+	using FManager::FManager;
+
+	bool Tick(float DeltaTime) final;
+};
+
+struct OPENAPI_API HttpRetryParams
+{
+	HttpRetryParams(
+		const FRetryLimitCountSetting& InRetryLimitCountOverride = FRetryLimitCountSetting(),
+		const FRetryTimeoutRelativeSecondsSetting& InRetryTimeoutRelativeSecondsOverride = FRetryTimeoutRelativeSecondsSetting(),
+		const FRetryResponseCodes& InRetryResponseCodes = FRetryResponseCodes(),
+		const FRetryVerbs& InRetryVerbs = FRetryVerbs(),
+		const FRetryDomainsPtr& InRetryDomains = FRetryDomainsPtr()
+	);
+
+	FRetryLimitCountSetting              RetryLimitCountOverride;
+	FRetryTimeoutRelativeSecondsSetting  RetryTimeoutRelativeSecondsOverride;
+	FRetryResponseCodes					 RetryResponseCodes;
+	FRetryVerbs                          RetryVerbs;
+	FRetryDomainsPtr					 RetryDomains;
+};
 
 class OPENAPI_API Model
 { 
@@ -37,11 +64,12 @@ class OPENAPI_API Request
 	virtual void SetupHttpRequest(const FHttpRequestRef& HttpRequest) const = 0;
 	virtual FString ComputePath() const = 0;
 
-	void SetAutoRetryCount(int InCount) { AutoRetryCount = InCount; }
-	int GetAutoRetryCount() const { return AutoRetryCount; }
+	/* Enables retry and optionally sets a retry policy for this request */
+	void SetShouldRetry(const HttpRetryParams& Params = HttpRetryParams()) { RetryParams = Params; }
+	const TOptional<HttpRetryParams>& GetRetryParams() const { return RetryParams; }
 
 private:
-	int AutoRetryCount = 0;
+	TOptional<HttpRetryParams> RetryParams;
 };
 
 class OPENAPI_API Response
@@ -53,8 +81,6 @@ class OPENAPI_API Response
 	void SetSuccessful(bool InSuccessful) { Successful = InSuccessful; }
 	bool IsSuccessful() const { return Successful; }
 
-	void AsyncRetry() const;
-
 	virtual void SetHttpResponseCode(EHttpResponseCodes::Type InHttpResponseCode);
 	EHttpResponseCodes::Type GetHttpResponseCode() const { return ResponseCode; }
 
@@ -64,15 +90,11 @@ class OPENAPI_API Response
 	void SetHttpResponse(const FHttpResponsePtr& InHttpResponse) { HttpResponse = InHttpResponse; }
 	const FHttpResponsePtr& GetHttpResponse() const { return HttpResponse; }
 
-	void SetHttpRequest(const FHttpRequestPtr& InHttpRequest) { HttpRequest = InHttpRequest; }
-	const FHttpRequestPtr& GetHttpRequest() const { return HttpRequest; }
-
 private:
 	bool Successful;
 	EHttpResponseCodes::Type ResponseCode;
 	FString ResponseString;
 	FHttpResponsePtr HttpResponse;
-	FHttpRequestPtr HttpRequest;
 };
 
 }
diff --git a/samples/client/petstore/cpp-ue4/Public/OpenAPIPetApi.h b/samples/client/petstore/cpp-ue4/Public/OpenAPIPetApi.h
index bde6403c4913..db422a0eccc6 100644
--- a/samples/client/petstore/cpp-ue4/Public/OpenAPIPetApi.h
+++ b/samples/client/petstore/cpp-ue4/Public/OpenAPIPetApi.h
@@ -24,9 +24,19 @@ class OPENAPI_API OpenAPIPetApi
 	OpenAPIPetApi();
 	~OpenAPIPetApi();
 
+	/* Sets the URL Endpoint. 
+	* Note: several fallback endpoints can be configured in request retry policies, see Request::SetShouldRetry */
 	void SetURL(const FString& Url);
+
+	/* Adds global header params to all requests */
 	void AddHeaderParam(const FString& Key, const FString& Value);
 	void ClearHeaderParams();
+	
+	/* Sets the retry manager to the user-defined retry manager. User must manage the lifetime of the retry manager.
+	* If no retry manager is specified and a request needs retries, a default retry manager will be used. 
+	* See also: Request::SetShouldRetry */
+	void SetHttpRetryManager(FHttpRetrySystem::FManager& RetryManager);
+	FHttpRetrySystem::FManager& GetHttpRetryManager();
 
 	class AddPetRequest;
 	class AddPetResponse;
@@ -63,22 +73,24 @@ class OPENAPI_API OpenAPIPetApi
     bool UpdatePetWithForm(const UpdatePetWithFormRequest& Request, const FUpdatePetWithFormDelegate& Delegate = FUpdatePetWithFormDelegate()) const;
     bool UploadFile(const UploadFileRequest& Request, const FUploadFileDelegate& Delegate = FUploadFileDelegate()) const;
     
-
 private:
-    void OnAddPetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FAddPetDelegate Delegate, int AutoRetryCount) const;
-    void OnDeletePetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeletePetDelegate Delegate, int AutoRetryCount) const;
-    void OnFindPetsByStatusResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FFindPetsByStatusDelegate Delegate, int AutoRetryCount) const;
-    void OnFindPetsByTagsResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FFindPetsByTagsDelegate Delegate, int AutoRetryCount) const;
-    void OnGetPetByIdResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetPetByIdDelegate Delegate, int AutoRetryCount) const;
-    void OnUpdatePetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdatePetDelegate Delegate, int AutoRetryCount) const;
-    void OnUpdatePetWithFormResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdatePetWithFormDelegate Delegate, int AutoRetryCount) const;
-    void OnUploadFileResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUploadFileDelegate Delegate, int AutoRetryCount) const;
+    void OnAddPetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FAddPetDelegate Delegate) const;
+    void OnDeletePetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeletePetDelegate Delegate) const;
+    void OnFindPetsByStatusResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FFindPetsByStatusDelegate Delegate) const;
+    void OnFindPetsByTagsResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FFindPetsByTagsDelegate Delegate) const;
+    void OnGetPetByIdResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetPetByIdDelegate Delegate) const;
+    void OnUpdatePetResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdatePetDelegate Delegate) const;
+    void OnUpdatePetWithFormResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdatePetWithFormDelegate Delegate) const;
+    void OnUploadFileResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUploadFileDelegate Delegate) const;
     
+	FHttpRequestRef CreateHttpRequest(const Request& Request) const;
 	bool IsValid() const;
 	void HandleResponse(FHttpResponsePtr HttpResponse, bool bSucceeded, Response& InOutResponse) const;
 
 	FString Url;
 	TMap<FString,FString> AdditionalHeaderParams;
+	mutable FHttpRetrySystem::FManager* RetryManager = nullptr;
+	mutable TUniquePtr<HttpRetryManager> DefaultRetryManager;
 };
 	
 }
diff --git a/samples/client/petstore/cpp-ue4/Public/OpenAPIStoreApi.h b/samples/client/petstore/cpp-ue4/Public/OpenAPIStoreApi.h
index 5f5377327328..934a1b277c74 100644
--- a/samples/client/petstore/cpp-ue4/Public/OpenAPIStoreApi.h
+++ b/samples/client/petstore/cpp-ue4/Public/OpenAPIStoreApi.h
@@ -24,9 +24,19 @@ class OPENAPI_API OpenAPIStoreApi
 	OpenAPIStoreApi();
 	~OpenAPIStoreApi();
 
+	/* Sets the URL Endpoint. 
+	* Note: several fallback endpoints can be configured in request retry policies, see Request::SetShouldRetry */
 	void SetURL(const FString& Url);
+
+	/* Adds global header params to all requests */
 	void AddHeaderParam(const FString& Key, const FString& Value);
 	void ClearHeaderParams();
+	
+	/* Sets the retry manager to the user-defined retry manager. User must manage the lifetime of the retry manager.
+	* If no retry manager is specified and a request needs retries, a default retry manager will be used. 
+	* See also: Request::SetShouldRetry */
+	void SetHttpRetryManager(FHttpRetrySystem::FManager& RetryManager);
+	FHttpRetrySystem::FManager& GetHttpRetryManager();
 
 	class DeleteOrderRequest;
 	class DeleteOrderResponse;
@@ -47,18 +57,20 @@ class OPENAPI_API OpenAPIStoreApi
     bool GetOrderById(const GetOrderByIdRequest& Request, const FGetOrderByIdDelegate& Delegate = FGetOrderByIdDelegate()) const;
     bool PlaceOrder(const PlaceOrderRequest& Request, const FPlaceOrderDelegate& Delegate = FPlaceOrderDelegate()) const;
     
-
 private:
-    void OnDeleteOrderResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeleteOrderDelegate Delegate, int AutoRetryCount) const;
-    void OnGetInventoryResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetInventoryDelegate Delegate, int AutoRetryCount) const;
-    void OnGetOrderByIdResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetOrderByIdDelegate Delegate, int AutoRetryCount) const;
-    void OnPlaceOrderResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FPlaceOrderDelegate Delegate, int AutoRetryCount) const;
+    void OnDeleteOrderResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeleteOrderDelegate Delegate) const;
+    void OnGetInventoryResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetInventoryDelegate Delegate) const;
+    void OnGetOrderByIdResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetOrderByIdDelegate Delegate) const;
+    void OnPlaceOrderResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FPlaceOrderDelegate Delegate) const;
     
+	FHttpRequestRef CreateHttpRequest(const Request& Request) const;
 	bool IsValid() const;
 	void HandleResponse(FHttpResponsePtr HttpResponse, bool bSucceeded, Response& InOutResponse) const;
 
 	FString Url;
 	TMap<FString,FString> AdditionalHeaderParams;
+	mutable FHttpRetrySystem::FManager* RetryManager = nullptr;
+	mutable TUniquePtr<HttpRetryManager> DefaultRetryManager;
 };
 	
 }
diff --git a/samples/client/petstore/cpp-ue4/Public/OpenAPIUserApi.h b/samples/client/petstore/cpp-ue4/Public/OpenAPIUserApi.h
index e60ce6754039..809c4950125b 100644
--- a/samples/client/petstore/cpp-ue4/Public/OpenAPIUserApi.h
+++ b/samples/client/petstore/cpp-ue4/Public/OpenAPIUserApi.h
@@ -24,9 +24,19 @@ class OPENAPI_API OpenAPIUserApi
 	OpenAPIUserApi();
 	~OpenAPIUserApi();
 
+	/* Sets the URL Endpoint. 
+	* Note: several fallback endpoints can be configured in request retry policies, see Request::SetShouldRetry */
 	void SetURL(const FString& Url);
+
+	/* Adds global header params to all requests */
 	void AddHeaderParam(const FString& Key, const FString& Value);
 	void ClearHeaderParams();
+	
+	/* Sets the retry manager to the user-defined retry manager. User must manage the lifetime of the retry manager.
+	* If no retry manager is specified and a request needs retries, a default retry manager will be used. 
+	* See also: Request::SetShouldRetry */
+	void SetHttpRetryManager(FHttpRetrySystem::FManager& RetryManager);
+	FHttpRetrySystem::FManager& GetHttpRetryManager();
 
 	class CreateUserRequest;
 	class CreateUserResponse;
@@ -63,22 +73,24 @@ class OPENAPI_API OpenAPIUserApi
     bool LogoutUser(const LogoutUserRequest& Request, const FLogoutUserDelegate& Delegate = FLogoutUserDelegate()) const;
     bool UpdateUser(const UpdateUserRequest& Request, const FUpdateUserDelegate& Delegate = FUpdateUserDelegate()) const;
     
-
 private:
-    void OnCreateUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUserDelegate Delegate, int AutoRetryCount) const;
-    void OnCreateUsersWithArrayInputResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUsersWithArrayInputDelegate Delegate, int AutoRetryCount) const;
-    void OnCreateUsersWithListInputResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUsersWithListInputDelegate Delegate, int AutoRetryCount) const;
-    void OnDeleteUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeleteUserDelegate Delegate, int AutoRetryCount) const;
-    void OnGetUserByNameResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetUserByNameDelegate Delegate, int AutoRetryCount) const;
-    void OnLoginUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FLoginUserDelegate Delegate, int AutoRetryCount) const;
-    void OnLogoutUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FLogoutUserDelegate Delegate, int AutoRetryCount) const;
-    void OnUpdateUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdateUserDelegate Delegate, int AutoRetryCount) const;
+    void OnCreateUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUserDelegate Delegate) const;
+    void OnCreateUsersWithArrayInputResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUsersWithArrayInputDelegate Delegate) const;
+    void OnCreateUsersWithListInputResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FCreateUsersWithListInputDelegate Delegate) const;
+    void OnDeleteUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FDeleteUserDelegate Delegate) const;
+    void OnGetUserByNameResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FGetUserByNameDelegate Delegate) const;
+    void OnLoginUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FLoginUserDelegate Delegate) const;
+    void OnLogoutUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FLogoutUserDelegate Delegate) const;
+    void OnUpdateUserResponse(FHttpRequestPtr HttpRequest, FHttpResponsePtr HttpResponse, bool bSucceeded, FUpdateUserDelegate Delegate) const;
     
+	FHttpRequestRef CreateHttpRequest(const Request& Request) const;
 	bool IsValid() const;
 	void HandleResponse(FHttpResponsePtr HttpResponse, bool bSucceeded, Response& InOutResponse) const;
 
 	FString Url;
 	TMap<FString,FString> AdditionalHeaderParams;
+	mutable FHttpRetrySystem::FManager* RetryManager = nullptr;
+	mutable TUniquePtr<HttpRetryManager> DefaultRetryManager;
 };
 	
 }

From 7703c923f9f93c39a977243a9f3ce36677c0c5ff Mon Sep 17 00:00:00 2001
From: William Cheng <wing328hk@gmail.com>
Date: Thu, 6 May 2021 12:14:45 +0800
Subject: [PATCH 15/18] update doc

---
 docs/contributing.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docs/contributing.md b/docs/contributing.md
index a791b0d6f1ba..fe325ae17e16 100644
--- a/docs/contributing.md
+++ b/docs/contributing.md
@@ -52,6 +52,7 @@ Code change should conform to the programming style guide of the respective lang
 - C#: https://msdn.microsoft.com/en-us/library/vstudio/ff926074.aspx
 - C++: https://google.github.io/styleguide/cppguide.html
 - C++ (Tizen): https://wiki.tizen.org/Native_Platform_Coding_Idiom_and_Style_Guide#C.2B.2B_Coding_Style
+- C++ (Unreal Engine 4): https://docs.unrealengine.com/en-US/ProductionPipelines/DevelopmentSetup/CodingStandard/index.html
 - Clojure: https://github.com/bbatsov/clojure-style-guide
 - Crystal: https://crystal-lang.org/reference/conventions/coding_style.html
 - Dart: https://www.dartlang.org/guides/language/effective-dart/style

From f4f4d5de0e5dec0e8d23e9faca197180e1f3fb3d Mon Sep 17 00:00:00 2001
From: Bruno Coelho <4brunu@users.noreply.github.com>
Date: Thu, 6 May 2021 17:26:22 +0100
Subject: [PATCH 16/18] [kotlin][client] fix warning for non optional header
 parameter (#9415)

---
 .../resources/kotlin-client/libraries/jvm-okhttp/api.mustache   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache
index 8adf1980e420..7745b52249ab 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache
@@ -97,7 +97,7 @@ import {{packageName}}.infrastructure.toMultiValue
             {{/hasQueryParams}}
         val localVariableHeaders: MutableMap<String, String> = mutableMapOf({{#hasFormParams}}"Content-Type" to {{^consumes}}"multipart/form-data"{{/consumes}}{{#consumes.0}}"{{{mediaType}}}"{{/consumes.0}}{{/hasFormParams}})
         {{#headerParams}}
-        {{{paramName}}}?.apply { localVariableHeaders["{{baseName}}"] = {{#isContainer}}this.joinToString(separator = collectionDelimiter("{{collectionFormat}}")){{/isContainer}}{{^isContainer}}this.toString(){{/isContainer}} }
+        {{{paramName}}}{{^required}}?{{/required}}.apply { localVariableHeaders["{{baseName}}"] = {{#isContainer}}this.joinToString(separator = collectionDelimiter("{{collectionFormat}}")){{/isContainer}}{{^isContainer}}this.toString(){{/isContainer}} }
         {{/headerParams}}
         
         val localVariableConfig = RequestConfig(

From 1dad148b698d142245efbcafe18fd317b7114970 Mon Sep 17 00:00:00 2001
From: Kyle Kelly <kkelly@yelp.com>
Date: Wed, 5 May 2021 14:08:02 -0700
Subject: [PATCH 17/18] Add handling for casting uniqueItems from Set to Arrays
 so they can be properly joined

---
 .../src/main/resources/Javascript-Flowtyped/api.mustache    | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/modules/openapi-generator/src/main/resources/Javascript-Flowtyped/api.mustache b/modules/openapi-generator/src/main/resources/Javascript-Flowtyped/api.mustache
index 35bff5b9687e..d7565ea7ceb6 100644
--- a/modules/openapi-generator/src/main/resources/Javascript-Flowtyped/api.mustache
+++ b/modules/openapi-generator/src/main/resources/Javascript-Flowtyped/api.mustache
@@ -142,7 +142,7 @@ export const {{classname}}FetchParamCreator = function (configuration?: Configur
                 localVarQueryParameter['{{baseName}}'] = {{paramName}};
             {{/isCollectionFormatMulti}}
             {{^isCollectionFormatMulti}}
-                localVarQueryParameter['{{baseName}}'] = {{paramName}}.join(COLLECTION_FORMATS["{{collectionFormat}}"]);
+                localVarQueryParameter['{{baseName}}'] = {{#uniqueItems}}Array.from({{/uniqueItems}}{{paramName}}{{#uniqueItems}}){{/uniqueItems}}.join(COLLECTION_FORMATS["{{collectionFormat}}"]);
             {{/isCollectionFormatMulti}}
             }
             {{/isArray}}
@@ -166,7 +166,7 @@ export const {{classname}}FetchParamCreator = function (configuration?: Configur
     {{#headerParams}}
             {{#isArray}}
             if ({{paramName}}) {
-                localVarHeaderParameter['{{baseName}}'] = {{paramName}}.join(COLLECTION_FORMATS["{{collectionFormat}}"]);
+                localVarHeaderParameter['{{baseName}}'] = {{#uniqueItems}}Array.from({{/uniqueItems}}{{paramName}}{{#uniqueItems}}){{/uniqueItems}}.join(COLLECTION_FORMATS["{{collectionFormat}}"]);
             }
             {{/isArray}}
             {{^isArray}}
@@ -185,7 +185,7 @@ export const {{classname}}FetchParamCreator = function (configuration?: Configur
                 })
             {{/isCollectionFormatMulti}}
             {{^isCollectionFormatMulti}}
-                    localVarFormParams.set('{{baseName}}', {{paramName}}.join(COLLECTION_FORMATS["{{collectionFormat}}"]));
+                    localVarFormParams.set('{{baseName}}', {{#uniqueItems}}Array.from({{/uniqueItems}}{{paramName}}{{#uniqueItems}}){{/uniqueItems}}.join(COLLECTION_FORMATS["{{collectionFormat}}"]));
             {{/isCollectionFormatMulti}}
             }
             {{/isArray}}

From cde69768c4071e825535acbad1592a116ebf3ffe Mon Sep 17 00:00:00 2001
From: Kyle Kelly <kkelly@yelp.com>
Date: Wed, 5 May 2021 14:08:19 -0700
Subject: [PATCH 18/18] Fix mixed-indent lines

---
 .../resources/Javascript-Flowtyped/api.mustache    | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/modules/openapi-generator/src/main/resources/Javascript-Flowtyped/api.mustache b/modules/openapi-generator/src/main/resources/Javascript-Flowtyped/api.mustache
index d7565ea7ceb6..1afc22037510 100644
--- a/modules/openapi-generator/src/main/resources/Javascript-Flowtyped/api.mustache
+++ b/modules/openapi-generator/src/main/resources/Javascript-Flowtyped/api.mustache
@@ -104,16 +104,16 @@ export const {{classname}}FetchParamCreator = function (configuration?: Configur
             {{#isKeyInHeader}}
             if (configuration && configuration.apiKey) {
                 const localVarApiKeyValue = typeof configuration.apiKey === 'function'
-					? configuration.apiKey("{{keyParamName}}")
-					: configuration.apiKey;
+                ? configuration.apiKey("{{keyParamName}}")
+                : configuration.apiKey;
                 localVarHeaderParameter["{{keyParamName}}"] = localVarApiKeyValue;
             }
             {{/isKeyInHeader}}
             {{#isKeyInQuery}}
             if (configuration && configuration.apiKey) {
                 const localVarApiKeyValue = typeof configuration.apiKey === 'function'
-					? configuration.apiKey("{{keyParamName}}")
-					: configuration.apiKey;
+                ? configuration.apiKey("{{keyParamName}}")
+                : configuration.apiKey;
                 localVarQueryParameter["{{keyParamName}}"] = localVarApiKeyValue;
             }
             {{/isKeyInQuery}}
@@ -127,9 +127,9 @@ export const {{classname}}FetchParamCreator = function (configuration?: Configur
             {{#isOAuth}}
             // oauth required
             if (configuration && configuration.accessToken) {
-				const localVarAccessTokenValue = typeof configuration.accessToken === 'function'
-					? configuration.accessToken("{{name}}", [{{#scopes}}"{{{scope}}}"{{^-last}}, {{/-last}}{{/scopes}}])
-					: configuration.accessToken;
+            const localVarAccessTokenValue = typeof configuration.accessToken === 'function'
+                ? configuration.accessToken("{{name}}", [{{#scopes}}"{{{scope}}}"{{^-last}}, {{/-last}}{{/scopes}}])
+                : configuration.accessToken;
                 localVarHeaderParameter["Authorization"] = "Bearer " + localVarAccessTokenValue;
             }
             {{/isOAuth}}