diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift4Codegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift4Codegen.java
index 24f55bfca31a..3bd931fd7dae 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift4Codegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift4Codegen.java
@@ -60,7 +60,7 @@ public class Swift4Codegen extends DefaultCodegen implements CodegenConfig {
     protected static final String LIBRARY_RX_SWIFT = "RxSwift";
     protected static final String[] RESPONSE_LIBRARIES = {LIBRARY_PROMISE_KIT, LIBRARY_RX_SWIFT};
     protected String projectName = "OpenAPIClient";
-    protected boolean unwrapRequired;
+    protected boolean unwrapRequired = true;
     protected boolean objcCompatible = false;
     protected boolean lenientTypeCast = false;
     protected boolean swiftUseApiNamespace;
diff --git a/modules/openapi-generator/src/main/resources/swift4/modelObject.mustache b/modules/openapi-generator/src/main/resources/swift4/modelObject.mustache
index d477ac7880d6..a98e8f245298 100644
--- a/modules/openapi-generator/src/main/resources/swift4/modelObject.mustache
+++ b/modules/openapi-generator/src/main/resources/swift4/modelObject.mustache
@@ -9,11 +9,11 @@ public struct {{classname}}: Codable {
 {{#allVars}}
 {{#isEnum}}
     {{#description}}/** {{description}} */
-    {{/description}}public var {{name}}: {{{datatypeWithEnum}}}{{#unwrapRequired}}?{{/unwrapRequired}}{{^unwrapRequired}}{{^required}}?{{/required}}{{/unwrapRequired}}{{#defaultValue}} = {{{defaultValue}}}{{/defaultValue}}
+    {{/description}}public var {{name}}: {{{datatypeWithEnum}}}{{^unwrapRequired}}?{{/unwrapRequired}}{{#unwrapRequired}}{{^required}}?{{/required}}{{/unwrapRequired}}{{#defaultValue}} = {{{defaultValue}}}{{/defaultValue}}
 {{/isEnum}}
 {{^isEnum}}
     {{#description}}/** {{description}} */
-    {{/description}}public var {{name}}: {{{datatype}}}{{#unwrapRequired}}?{{/unwrapRequired}}{{^unwrapRequired}}{{^required}}?{{/required}}{{/unwrapRequired}}{{#defaultValue}} = {{{defaultValue}}}{{/defaultValue}}{{#objcCompatible}}{{#vendorExtensions.x-swift-optional-scalar}}
+    {{/description}}public var {{name}}: {{{datatype}}}{{^unwrapRequired}}?{{/unwrapRequired}}{{#unwrapRequired}}{{^required}}?{{/required}}{{/unwrapRequired}}{{#defaultValue}} = {{{defaultValue}}}{{/defaultValue}}{{#objcCompatible}}{{#vendorExtensions.x-swift-optional-scalar}}
     public var {{name}}Num: NSNumber? {
         get {
             return {{name}}.map({ return NSNumber(value: $0) })
@@ -23,7 +23,7 @@ public struct {{classname}}: Codable {
 {{/allVars}}
 
 {{#hasVars}}
-    public init({{#allVars}}{{name}}: {{{datatypeWithEnum}}}{{#unwrapRequired}}?{{/unwrapRequired}}{{^unwrapRequired}}{{^required}}?{{/required}}{{/unwrapRequired}}{{#hasMore}}, {{/hasMore}}{{/allVars}}) {
+    public init({{#allVars}}{{name}}: {{{datatypeWithEnum}}}{{^unwrapRequired}}?{{/unwrapRequired}}{{#unwrapRequired}}{{^required}}?{{/required}}{{/unwrapRequired}}{{#hasMore}}, {{/hasMore}}{{/allVars}}) {
         {{#allVars}}
         self.{{name}} = {{name}}
         {{/allVars}}
@@ -52,7 +52,7 @@ public struct {{classname}}: Codable {
         var container = encoder.container(keyedBy: String.self)
 
         {{#allVars}}
-        try container.encode{{#unwrapRequired}}IfPresent{{/unwrapRequired}}{{^unwrapRequired}}{{^required}}IfPresent{{/required}}{{/unwrapRequired}}({{{name}}}, forKey: "{{{baseName}}}")
+        try container.encode{{^unwrapRequired}}IfPresent{{/unwrapRequired}}{{#unwrapRequired}}{{^required}}IfPresent{{/required}}{{/unwrapRequired}}({{{name}}}, forKey: "{{{baseName}}}")
         {{/allVars}}
         try container.encodeMap(additionalProperties)
     }
@@ -63,7 +63,7 @@ public struct {{classname}}: Codable {
         let container = try decoder.container(keyedBy: String.self)
 
         {{#allVars}}
-        {{name}} = try container.decode{{#unwrapRequired}}IfPresent{{/unwrapRequired}}{{^unwrapRequired}}{{^required}}IfPresent{{/required}}{{/unwrapRequired}}({{{datatypeWithEnum}}}.self, forKey: "{{{baseName}}}")
+        {{name}} = try container.decode{{^unwrapRequired}}IfPresent{{/unwrapRequired}}{{#unwrapRequired}}{{^required}}IfPresent{{/required}}{{/unwrapRequired}}({{{datatypeWithEnum}}}.self, forKey: "{{{baseName}}}")
         {{/allVars}}
         var nonAdditionalPropertyKeys = Set<String>()
         {{#allVars}}
diff --git a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/AnotherFakeAPI.swift b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/AnotherFakeAPI.swift
index a044abe9b92c..ffecb66c48c2 100644
--- a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/AnotherFakeAPI.swift
+++ b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/AnotherFakeAPI.swift
@@ -14,11 +14,11 @@ open class AnotherFakeAPI {
     /**
      To test special tags
      
-     - parameter client: (body) client model 
+     - parameter body: (body) client model 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func call123testSpecialTags(client: Client, completion: @escaping ((_ data: Client?,_ error: Error?) -> Void)) {
-        call123testSpecialTagsWithRequestBuilder(client: client).execute { (response, error) -> Void in
+    open class func call123testSpecialTags(body: Client, completion: @escaping ((_ data: Client?,_ error: Error?) -> Void)) {
+        call123testSpecialTagsWithRequestBuilder(body: body).execute { (response, error) -> Void in
             completion(response?.body, error)
         }
     }
@@ -27,13 +27,13 @@ open class AnotherFakeAPI {
      To test special tags
      - PATCH /another-fake/dummy
      - To test special tags and operation ID starting with number
-     - parameter client: (body) client model 
+     - parameter body: (body) client model 
      - returns: RequestBuilder<Client> 
      */
-    open class func call123testSpecialTagsWithRequestBuilder(client: Client) -> RequestBuilder<Client> {
+    open class func call123testSpecialTagsWithRequestBuilder(body: Client) -> RequestBuilder<Client> {
         let path = "/another-fake/dummy"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: client)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
diff --git a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/FakeAPI.swift b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/FakeAPI.swift
index c6b61d04576d..2bfd5a21d7a3 100644
--- a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/FakeAPI.swift
+++ b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/FakeAPI.swift
@@ -11,6 +11,41 @@ import Alamofire
 
 
 open class FakeAPI {
+    /**
+     creates an XmlItem
+     
+     - parameter xmlItem: (body) XmlItem Body 
+     - parameter completion: completion handler to receive the data and the error objects
+     */
+    open class func createXmlItem(xmlItem: XmlItem, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
+        createXmlItemWithRequestBuilder(xmlItem: xmlItem).execute { (response, error) -> Void in
+            if error == nil {
+                completion((), error)
+            } else {
+                completion(nil, error)
+            }
+        }
+    }
+
+    /**
+     creates an XmlItem
+     - POST /fake/create_xml_item
+     - this route creates an XmlItem
+     - parameter xmlItem: (body) XmlItem Body 
+     - returns: RequestBuilder<Void> 
+     */
+    open class func createXmlItemWithRequestBuilder(xmlItem: XmlItem) -> RequestBuilder<Void> {
+        let path = "/fake/create_xml_item"
+        let URLString = PetstoreClientAPI.basePath + path
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: xmlItem)
+
+        let url = URLComponents(string: URLString)
+
+        let requestBuilder: RequestBuilder<Void>.Type = PetstoreClientAPI.requestBuilderFactory.getNonDecodableBuilder()
+
+        return requestBuilder.init(method: "POST", URLString: (url?.string ?? URLString), parameters: parameters, isBody: true)
+    }
+
     /**
 
      - parameter body: (body) Input boolean as post body (optional)
@@ -42,11 +77,11 @@ open class FakeAPI {
 
     /**
 
-     - parameter outerComposite: (body) Input composite as post body (optional)
+     - parameter body: (body) Input composite as post body (optional)
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func fakeOuterCompositeSerialize(outerComposite: OuterComposite? = nil, completion: @escaping ((_ data: OuterComposite?,_ error: Error?) -> Void)) {
-        fakeOuterCompositeSerializeWithRequestBuilder(outerComposite: outerComposite).execute { (response, error) -> Void in
+    open class func fakeOuterCompositeSerialize(body: OuterComposite? = nil, completion: @escaping ((_ data: OuterComposite?,_ error: Error?) -> Void)) {
+        fakeOuterCompositeSerializeWithRequestBuilder(body: body).execute { (response, error) -> Void in
             completion(response?.body, error)
         }
     }
@@ -54,13 +89,13 @@ open class FakeAPI {
     /**
      - POST /fake/outer/composite
      - Test serialization of object with outer number type
-     - parameter outerComposite: (body) Input composite as post body (optional)
+     - parameter body: (body) Input composite as post body (optional)
      - returns: RequestBuilder<OuterComposite> 
      */
-    open class func fakeOuterCompositeSerializeWithRequestBuilder(outerComposite: OuterComposite? = nil) -> RequestBuilder<OuterComposite> {
+    open class func fakeOuterCompositeSerializeWithRequestBuilder(body: OuterComposite? = nil) -> RequestBuilder<OuterComposite> {
         let path = "/fake/outer/composite"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: outerComposite)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
@@ -129,11 +164,11 @@ open class FakeAPI {
 
     /**
 
-     - parameter fileSchemaTestClass: (body)  
+     - parameter body: (body)  
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func testBodyWithFileSchema(fileSchemaTestClass: FileSchemaTestClass, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
-        testBodyWithFileSchemaWithRequestBuilder(fileSchemaTestClass: fileSchemaTestClass).execute { (response, error) -> Void in
+    open class func testBodyWithFileSchema(body: FileSchemaTestClass, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
+        testBodyWithFileSchemaWithRequestBuilder(body: body).execute { (response, error) -> Void in
             if error == nil {
                 completion((), error)
             } else {
@@ -145,13 +180,13 @@ open class FakeAPI {
     /**
      - PUT /fake/body-with-file-schema
      - For this test, the body for this request much reference a schema named `File`.
-     - parameter fileSchemaTestClass: (body)  
+     - parameter body: (body)  
      - returns: RequestBuilder<Void> 
      */
-    open class func testBodyWithFileSchemaWithRequestBuilder(fileSchemaTestClass: FileSchemaTestClass) -> RequestBuilder<Void> {
+    open class func testBodyWithFileSchemaWithRequestBuilder(body: FileSchemaTestClass) -> RequestBuilder<Void> {
         let path = "/fake/body-with-file-schema"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: fileSchemaTestClass)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
@@ -163,11 +198,11 @@ open class FakeAPI {
     /**
 
      - parameter query: (query)  
-     - parameter user: (body)  
+     - parameter body: (body)  
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func testBodyWithQueryParams(query: String, user: User, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
-        testBodyWithQueryParamsWithRequestBuilder(query: query, user: user).execute { (response, error) -> Void in
+    open class func testBodyWithQueryParams(query: String, body: User, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
+        testBodyWithQueryParamsWithRequestBuilder(query: query, body: body).execute { (response, error) -> Void in
             if error == nil {
                 completion((), error)
             } else {
@@ -179,13 +214,13 @@ open class FakeAPI {
     /**
      - PUT /fake/body-with-query-params
      - parameter query: (query)  
-     - parameter user: (body)  
+     - parameter body: (body)  
      - returns: RequestBuilder<Void> 
      */
-    open class func testBodyWithQueryParamsWithRequestBuilder(query: String, user: User) -> RequestBuilder<Void> {
+    open class func testBodyWithQueryParamsWithRequestBuilder(query: String, body: User) -> RequestBuilder<Void> {
         let path = "/fake/body-with-query-params"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: user)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         var url = URLComponents(string: URLString)
         url?.queryItems = APIHelper.mapValuesToQueryItems([
@@ -200,11 +235,11 @@ open class FakeAPI {
     /**
      To test \"client\" model
      
-     - parameter client: (body) client model 
+     - parameter body: (body) client model 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func testClientModel(client: Client, completion: @escaping ((_ data: Client?,_ error: Error?) -> Void)) {
-        testClientModelWithRequestBuilder(client: client).execute { (response, error) -> Void in
+    open class func testClientModel(body: Client, completion: @escaping ((_ data: Client?,_ error: Error?) -> Void)) {
+        testClientModelWithRequestBuilder(body: body).execute { (response, error) -> Void in
             completion(response?.body, error)
         }
     }
@@ -213,13 +248,13 @@ open class FakeAPI {
      To test \"client\" model
      - PATCH /fake
      - To test \"client\" model
-     - parameter client: (body) client model 
+     - parameter body: (body) client model 
      - returns: RequestBuilder<Client> 
      */
-    open class func testClientModelWithRequestBuilder(client: Client) -> RequestBuilder<Client> {
+    open class func testClientModelWithRequestBuilder(body: Client) -> RequestBuilder<Client> {
         let path = "/fake"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: client)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
@@ -502,11 +537,11 @@ open class FakeAPI {
     /**
      test inline additionalProperties
      
-     - parameter requestBody: (body) request body 
+     - parameter param: (body) request body 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func testInlineAdditionalProperties(requestBody: [String:String], completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
-        testInlineAdditionalPropertiesWithRequestBuilder(requestBody: requestBody).execute { (response, error) -> Void in
+    open class func testInlineAdditionalProperties(param: [String:String], completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
+        testInlineAdditionalPropertiesWithRequestBuilder(param: param).execute { (response, error) -> Void in
             if error == nil {
                 completion((), error)
             } else {
@@ -518,13 +553,13 @@ open class FakeAPI {
     /**
      test inline additionalProperties
      - POST /fake/inline-additionalProperties
-     - parameter requestBody: (body) request body 
+     - parameter param: (body) request body 
      - returns: RequestBuilder<Void> 
      */
-    open class func testInlineAdditionalPropertiesWithRequestBuilder(requestBody: [String:String]) -> RequestBuilder<Void> {
+    open class func testInlineAdditionalPropertiesWithRequestBuilder(param: [String:String]) -> RequestBuilder<Void> {
         let path = "/fake/inline-additionalProperties"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: requestBody)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: param)
 
         let url = URLComponents(string: URLString)
 
diff --git a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/FakeClassnameTags123API.swift b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/FakeClassnameTags123API.swift
index 1b4e3e1bfe31..ddfeae23edd0 100644
--- a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/FakeClassnameTags123API.swift
+++ b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/FakeClassnameTags123API.swift
@@ -14,11 +14,11 @@ open class FakeClassnameTags123API {
     /**
      To test class name in snake case
      
-     - parameter client: (body) client model 
+     - parameter body: (body) client model 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func testClassname(client: Client, completion: @escaping ((_ data: Client?,_ error: Error?) -> Void)) {
-        testClassnameWithRequestBuilder(client: client).execute { (response, error) -> Void in
+    open class func testClassname(body: Client, completion: @escaping ((_ data: Client?,_ error: Error?) -> Void)) {
+        testClassnameWithRequestBuilder(body: body).execute { (response, error) -> Void in
             completion(response?.body, error)
         }
     }
@@ -30,13 +30,13 @@ open class FakeClassnameTags123API {
      - API Key:
        - type: apiKey api_key_query (QUERY)
        - name: api_key_query
-     - parameter client: (body) client model 
+     - parameter body: (body) client model 
      - returns: RequestBuilder<Client> 
      */
-    open class func testClassnameWithRequestBuilder(client: Client) -> RequestBuilder<Client> {
+    open class func testClassnameWithRequestBuilder(body: Client) -> RequestBuilder<Client> {
         let path = "/fake_classname_test"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: client)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
diff --git a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/PetAPI.swift b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/PetAPI.swift
index 93795982089c..65a3d531ef72 100644
--- a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/PetAPI.swift
+++ b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/PetAPI.swift
@@ -14,11 +14,11 @@ open class PetAPI {
     /**
      Add a new pet to the store
      
-     - parameter pet: (body) Pet object that needs to be added to the store 
+     - parameter body: (body) Pet object that needs to be added to the store 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func addPet(pet: Pet, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
-        addPetWithRequestBuilder(pet: pet).execute { (response, error) -> Void in
+    open class func addPet(body: Pet, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
+        addPetWithRequestBuilder(body: body).execute { (response, error) -> Void in
             if error == nil {
                 completion((), error)
             } else {
@@ -33,13 +33,13 @@ open class PetAPI {
      - OAuth:
        - type: oauth2
        - name: petstore_auth
-     - parameter pet: (body) Pet object that needs to be added to the store 
+     - parameter body: (body) Pet object that needs to be added to the store 
      - returns: RequestBuilder<Void> 
      */
-    open class func addPetWithRequestBuilder(pet: Pet) -> RequestBuilder<Void> {
+    open class func addPetWithRequestBuilder(body: Pet) -> RequestBuilder<Void> {
         let path = "/pet"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: pet)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
@@ -217,11 +217,11 @@ open class PetAPI {
     /**
      Update an existing pet
      
-     - parameter pet: (body) Pet object that needs to be added to the store 
+     - parameter body: (body) Pet object that needs to be added to the store 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func updatePet(pet: Pet, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
-        updatePetWithRequestBuilder(pet: pet).execute { (response, error) -> Void in
+    open class func updatePet(body: Pet, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
+        updatePetWithRequestBuilder(body: body).execute { (response, error) -> Void in
             if error == nil {
                 completion((), error)
             } else {
@@ -236,13 +236,13 @@ open class PetAPI {
      - OAuth:
        - type: oauth2
        - name: petstore_auth
-     - parameter pet: (body) Pet object that needs to be added to the store 
+     - parameter body: (body) Pet object that needs to be added to the store 
      - returns: RequestBuilder<Void> 
      */
-    open class func updatePetWithRequestBuilder(pet: Pet) -> RequestBuilder<Void> {
+    open class func updatePetWithRequestBuilder(body: Pet) -> RequestBuilder<Void> {
         let path = "/pet"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: pet)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
diff --git a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/StoreAPI.swift b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/StoreAPI.swift
index 3b214f6881c3..f07183262c5e 100644
--- a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/StoreAPI.swift
+++ b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/StoreAPI.swift
@@ -118,11 +118,11 @@ open class StoreAPI {
     /**
      Place an order for a pet
      
-     - parameter order: (body) order placed for purchasing the pet 
+     - parameter body: (body) order placed for purchasing the pet 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func placeOrder(order: Order, completion: @escaping ((_ data: Order?,_ error: Error?) -> Void)) {
-        placeOrderWithRequestBuilder(order: order).execute { (response, error) -> Void in
+    open class func placeOrder(body: Order, completion: @escaping ((_ data: Order?,_ error: Error?) -> Void)) {
+        placeOrderWithRequestBuilder(body: body).execute { (response, error) -> Void in
             completion(response?.body, error)
         }
     }
@@ -130,13 +130,13 @@ open class StoreAPI {
     /**
      Place an order for a pet
      - POST /store/order
-     - parameter order: (body) order placed for purchasing the pet 
+     - parameter body: (body) order placed for purchasing the pet 
      - returns: RequestBuilder<Order> 
      */
-    open class func placeOrderWithRequestBuilder(order: Order) -> RequestBuilder<Order> {
+    open class func placeOrderWithRequestBuilder(body: Order) -> RequestBuilder<Order> {
         let path = "/store/order"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: order)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
diff --git a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/UserAPI.swift b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/UserAPI.swift
index f3f9136ec58c..eeb8a17efe4e 100644
--- a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/UserAPI.swift
+++ b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/APIs/UserAPI.swift
@@ -14,11 +14,11 @@ open class UserAPI {
     /**
      Create user
      
-     - parameter user: (body) Created user object 
+     - parameter body: (body) Created user object 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func createUser(user: User, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
-        createUserWithRequestBuilder(user: user).execute { (response, error) -> Void in
+    open class func createUser(body: User, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
+        createUserWithRequestBuilder(body: body).execute { (response, error) -> Void in
             if error == nil {
                 completion((), error)
             } else {
@@ -31,13 +31,13 @@ open class UserAPI {
      Create user
      - POST /user
      - This can only be done by the logged in user.
-     - parameter user: (body) Created user object 
+     - parameter body: (body) Created user object 
      - returns: RequestBuilder<Void> 
      */
-    open class func createUserWithRequestBuilder(user: User) -> RequestBuilder<Void> {
+    open class func createUserWithRequestBuilder(body: User) -> RequestBuilder<Void> {
         let path = "/user"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: user)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
@@ -49,11 +49,11 @@ open class UserAPI {
     /**
      Creates list of users with given input array
      
-     - parameter user: (body) List of user object 
+     - parameter body: (body) List of user object 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func createUsersWithArrayInput(user: [User], completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
-        createUsersWithArrayInputWithRequestBuilder(user: user).execute { (response, error) -> Void in
+    open class func createUsersWithArrayInput(body: [User], completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
+        createUsersWithArrayInputWithRequestBuilder(body: body).execute { (response, error) -> Void in
             if error == nil {
                 completion((), error)
             } else {
@@ -65,13 +65,13 @@ open class UserAPI {
     /**
      Creates list of users with given input array
      - POST /user/createWithArray
-     - parameter user: (body) List of user object 
+     - parameter body: (body) List of user object 
      - returns: RequestBuilder<Void> 
      */
-    open class func createUsersWithArrayInputWithRequestBuilder(user: [User]) -> RequestBuilder<Void> {
+    open class func createUsersWithArrayInputWithRequestBuilder(body: [User]) -> RequestBuilder<Void> {
         let path = "/user/createWithArray"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: user)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
@@ -83,11 +83,11 @@ open class UserAPI {
     /**
      Creates list of users with given input array
      
-     - parameter user: (body) List of user object 
+     - parameter body: (body) List of user object 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func createUsersWithListInput(user: [User], completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
-        createUsersWithListInputWithRequestBuilder(user: user).execute { (response, error) -> Void in
+    open class func createUsersWithListInput(body: [User], completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
+        createUsersWithListInputWithRequestBuilder(body: body).execute { (response, error) -> Void in
             if error == nil {
                 completion((), error)
             } else {
@@ -99,13 +99,13 @@ open class UserAPI {
     /**
      Creates list of users with given input array
      - POST /user/createWithList
-     - parameter user: (body) List of user object 
+     - parameter body: (body) List of user object 
      - returns: RequestBuilder<Void> 
      */
-    open class func createUsersWithListInputWithRequestBuilder(user: [User]) -> RequestBuilder<Void> {
+    open class func createUsersWithListInputWithRequestBuilder(body: [User]) -> RequestBuilder<Void> {
         let path = "/user/createWithList"
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: user)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
@@ -258,11 +258,11 @@ open class UserAPI {
      Updated user
      
      - parameter username: (path) name that need to be deleted 
-     - parameter user: (body) Updated user object 
+     - parameter body: (body) Updated user object 
      - parameter completion: completion handler to receive the data and the error objects
      */
-    open class func updateUser(username: String, user: User, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
-        updateUserWithRequestBuilder(username: username, user: user).execute { (response, error) -> Void in
+    open class func updateUser(username: String, body: User, completion: @escaping ((_ data: Void?,_ error: Error?) -> Void)) {
+        updateUserWithRequestBuilder(username: username, body: body).execute { (response, error) -> Void in
             if error == nil {
                 completion((), error)
             } else {
@@ -276,16 +276,16 @@ open class UserAPI {
      - PUT /user/{username}
      - This can only be done by the logged in user.
      - parameter username: (path) name that need to be deleted 
-     - parameter user: (body) Updated user object 
+     - parameter body: (body) Updated user object 
      - returns: RequestBuilder<Void> 
      */
-    open class func updateUserWithRequestBuilder(username: String, user: User) -> RequestBuilder<Void> {
+    open class func updateUserWithRequestBuilder(username: String, body: User) -> RequestBuilder<Void> {
         var path = "/user/{username}"
         let usernamePreEscape = "\(username)"
         let usernamePostEscape = usernamePreEscape.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) ?? ""
         path = path.replacingOccurrences(of: "{username}", with: usernamePostEscape, options: .literal, range: nil)
         let URLString = PetstoreClientAPI.basePath + path
-        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: user)
+        let parameters = JSONEncodingHelper.encodingParameters(forEncodableObject: body)
 
         let url = URLComponents(string: URLString)
 
diff --git a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/Models/TypeHolderDefault.swift b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/Models/TypeHolderDefault.swift
new file mode 100644
index 000000000000..be1afdf0266c
--- /dev/null
+++ b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/Models/TypeHolderDefault.swift
@@ -0,0 +1,38 @@
+//
+// TypeHolderDefault.swift
+//
+// Generated by openapi-generator
+// https://openapi-generator.tech
+//
+
+import Foundation
+
+
+
+public struct TypeHolderDefault: Codable {
+
+    public var stringItem: String = "what"
+    public var numberItem: Double
+    public var integerItem: Int
+    public var boolItem: Bool = true
+    public var arrayItem: [Int]
+
+    public init(stringItem: String, numberItem: Double, integerItem: Int, boolItem: Bool, arrayItem: [Int]) {
+        self.stringItem = stringItem
+        self.numberItem = numberItem
+        self.integerItem = integerItem
+        self.boolItem = boolItem
+        self.arrayItem = arrayItem
+    }
+
+    public enum CodingKeys: String, CodingKey { 
+        case stringItem = "string_item"
+        case numberItem = "number_item"
+        case integerItem = "integer_item"
+        case boolItem = "bool_item"
+        case arrayItem = "array_item"
+    }
+
+
+}
+
diff --git a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/Models/TypeHolderExample.swift b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/Models/TypeHolderExample.swift
new file mode 100644
index 000000000000..f46c8952e13e
--- /dev/null
+++ b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/Models/TypeHolderExample.swift
@@ -0,0 +1,38 @@
+//
+// TypeHolderExample.swift
+//
+// Generated by openapi-generator
+// https://openapi-generator.tech
+//
+
+import Foundation
+
+
+
+public struct TypeHolderExample: Codable {
+
+    public var stringItem: String
+    public var numberItem: Double
+    public var integerItem: Int
+    public var boolItem: Bool
+    public var arrayItem: [Int]
+
+    public init(stringItem: String, numberItem: Double, integerItem: Int, boolItem: Bool, arrayItem: [Int]) {
+        self.stringItem = stringItem
+        self.numberItem = numberItem
+        self.integerItem = integerItem
+        self.boolItem = boolItem
+        self.arrayItem = arrayItem
+    }
+
+    public enum CodingKeys: String, CodingKey { 
+        case stringItem = "string_item"
+        case numberItem = "number_item"
+        case integerItem = "integer_item"
+        case boolItem = "bool_item"
+        case arrayItem = "array_item"
+    }
+
+
+}
+
diff --git a/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/Models/XmlItem.swift b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/Models/XmlItem.swift
new file mode 100644
index 000000000000..e1b1ace8b153
--- /dev/null
+++ b/samples/client/petstore/swift4/default/PetstoreClient/Classes/OpenAPIs/Models/XmlItem.swift
@@ -0,0 +1,110 @@
+//
+// XmlItem.swift
+//
+// Generated by openapi-generator
+// https://openapi-generator.tech
+//
+
+import Foundation
+
+
+
+public struct XmlItem: Codable {
+
+    public var attributeString: String?
+    public var attributeNumber: Double?
+    public var attributeInteger: Int?
+    public var attributeBoolean: Bool?
+    public var wrappedArray: [Int]?
+    public var nameString: String?
+    public var nameNumber: Double?
+    public var nameInteger: Int?
+    public var nameBoolean: Bool?
+    public var nameArray: [Int]?
+    public var nameWrappedArray: [Int]?
+    public var prefixString: String?
+    public var prefixNumber: Double?
+    public var prefixInteger: Int?
+    public var prefixBoolean: Bool?
+    public var prefixArray: [Int]?
+    public var prefixWrappedArray: [Int]?
+    public var namespaceString: String?
+    public var namespaceNumber: Double?
+    public var namespaceInteger: Int?
+    public var namespaceBoolean: Bool?
+    public var namespaceArray: [Int]?
+    public var namespaceWrappedArray: [Int]?
+    public var prefixNsString: String?
+    public var prefixNsNumber: Double?
+    public var prefixNsInteger: Int?
+    public var prefixNsBoolean: Bool?
+    public var prefixNsArray: [Int]?
+    public var prefixNsWrappedArray: [Int]?
+
+    public init(attributeString: String?, attributeNumber: Double?, attributeInteger: Int?, attributeBoolean: Bool?, wrappedArray: [Int]?, nameString: String?, nameNumber: Double?, nameInteger: Int?, nameBoolean: Bool?, nameArray: [Int]?, nameWrappedArray: [Int]?, prefixString: String?, prefixNumber: Double?, prefixInteger: Int?, prefixBoolean: Bool?, prefixArray: [Int]?, prefixWrappedArray: [Int]?, namespaceString: String?, namespaceNumber: Double?, namespaceInteger: Int?, namespaceBoolean: Bool?, namespaceArray: [Int]?, namespaceWrappedArray: [Int]?, prefixNsString: String?, prefixNsNumber: Double?, prefixNsInteger: Int?, prefixNsBoolean: Bool?, prefixNsArray: [Int]?, prefixNsWrappedArray: [Int]?) {
+        self.attributeString = attributeString
+        self.attributeNumber = attributeNumber
+        self.attributeInteger = attributeInteger
+        self.attributeBoolean = attributeBoolean
+        self.wrappedArray = wrappedArray
+        self.nameString = nameString
+        self.nameNumber = nameNumber
+        self.nameInteger = nameInteger
+        self.nameBoolean = nameBoolean
+        self.nameArray = nameArray
+        self.nameWrappedArray = nameWrappedArray
+        self.prefixString = prefixString
+        self.prefixNumber = prefixNumber
+        self.prefixInteger = prefixInteger
+        self.prefixBoolean = prefixBoolean
+        self.prefixArray = prefixArray
+        self.prefixWrappedArray = prefixWrappedArray
+        self.namespaceString = namespaceString
+        self.namespaceNumber = namespaceNumber
+        self.namespaceInteger = namespaceInteger
+        self.namespaceBoolean = namespaceBoolean
+        self.namespaceArray = namespaceArray
+        self.namespaceWrappedArray = namespaceWrappedArray
+        self.prefixNsString = prefixNsString
+        self.prefixNsNumber = prefixNsNumber
+        self.prefixNsInteger = prefixNsInteger
+        self.prefixNsBoolean = prefixNsBoolean
+        self.prefixNsArray = prefixNsArray
+        self.prefixNsWrappedArray = prefixNsWrappedArray
+    }
+
+    public enum CodingKeys: String, CodingKey { 
+        case attributeString = "attribute_string"
+        case attributeNumber = "attribute_number"
+        case attributeInteger = "attribute_integer"
+        case attributeBoolean = "attribute_boolean"
+        case wrappedArray = "wrapped_array"
+        case nameString = "name_string"
+        case nameNumber = "name_number"
+        case nameInteger = "name_integer"
+        case nameBoolean = "name_boolean"
+        case nameArray = "name_array"
+        case nameWrappedArray = "name_wrapped_array"
+        case prefixString = "prefix_string"
+        case prefixNumber = "prefix_number"
+        case prefixInteger = "prefix_integer"
+        case prefixBoolean = "prefix_boolean"
+        case prefixArray = "prefix_array"
+        case prefixWrappedArray = "prefix_wrapped_array"
+        case namespaceString = "namespace_string"
+        case namespaceNumber = "namespace_number"
+        case namespaceInteger = "namespace_integer"
+        case namespaceBoolean = "namespace_boolean"
+        case namespaceArray = "namespace_array"
+        case namespaceWrappedArray = "namespace_wrapped_array"
+        case prefixNsString = "prefix_ns_string"
+        case prefixNsNumber = "prefix_ns_number"
+        case prefixNsInteger = "prefix_ns_integer"
+        case prefixNsBoolean = "prefix_ns_boolean"
+        case prefixNsArray = "prefix_ns_array"
+        case prefixNsWrappedArray = "prefix_ns_wrapped_array"
+    }
+
+
+}
+
diff --git a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Animal.swift b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Animal.swift
index befb84b1dfa4..7221a1be099d 100644
--- a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Animal.swift
+++ b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Animal.swift
@@ -11,10 +11,10 @@ import Foundation
 
 public struct Animal: Codable {
 
-    public var className: String?
+    public var className: String
     public var color: String? = "red"
 
-    public init(className: String?, color: String?) {
+    public init(className: String, color: String?) {
         self.className = className
         self.color = color
     }
diff --git a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Cat.swift b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Cat.swift
index c83ab1d0d974..a116d964ea84 100644
--- a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Cat.swift
+++ b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Cat.swift
@@ -11,11 +11,11 @@ import Foundation
 
 public struct Cat: Codable {
 
-    public var className: String?
+    public var className: String
     public var color: String? = "red"
     public var declawed: Bool?
 
-    public init(className: String?, color: String?, declawed: Bool?) {
+    public init(className: String, color: String?, declawed: Bool?) {
         self.className = className
         self.color = color
         self.declawed = declawed
diff --git a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Category.swift b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Category.swift
index f369f382d3f2..afdc89b6dd06 100644
--- a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Category.swift
+++ b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Category.swift
@@ -12,9 +12,9 @@ import Foundation
 public struct Category: Codable {
 
     public var _id: Int64?
-    public var name: String? = "default-name"
+    public var name: String = "default-name"
 
-    public init(_id: Int64?, name: String?) {
+    public init(_id: Int64?, name: String) {
         self._id = _id
         self.name = name
     }
diff --git a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Dog.swift b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Dog.swift
index 9a3016495335..239ce74dcc21 100644
--- a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Dog.swift
+++ b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Dog.swift
@@ -11,11 +11,11 @@ import Foundation
 
 public struct Dog: Codable {
 
-    public var className: String?
+    public var className: String
     public var color: String? = "red"
     public var breed: String?
 
-    public init(className: String?, color: String?, breed: String?) {
+    public init(className: String, color: String?, breed: String?) {
         self.className = className
         self.color = color
         self.breed = breed
diff --git a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/EnumTest.swift b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/EnumTest.swift
index ed93ec357bdf..0f546c76a218 100644
--- a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/EnumTest.swift
+++ b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/EnumTest.swift
@@ -30,12 +30,12 @@ public struct EnumTest: Codable {
         case number12 = -1.2
     }
     public var enumString: EnumString?
-    public var enumStringRequired: EnumStringRequired?
+    public var enumStringRequired: EnumStringRequired
     public var enumInteger: EnumInteger?
     public var enumNumber: EnumNumber?
     public var outerEnum: OuterEnum?
 
-    public init(enumString: EnumString?, enumStringRequired: EnumStringRequired?, enumInteger: EnumInteger?, enumNumber: EnumNumber?, outerEnum: OuterEnum?) {
+    public init(enumString: EnumString?, enumStringRequired: EnumStringRequired, enumInteger: EnumInteger?, enumNumber: EnumNumber?, outerEnum: OuterEnum?) {
         self.enumString = enumString
         self.enumStringRequired = enumStringRequired
         self.enumInteger = enumInteger
diff --git a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/FormatTest.swift b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/FormatTest.swift
index 7b26d8d80e47..faa091b0658c 100644
--- a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/FormatTest.swift
+++ b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/FormatTest.swift
@@ -14,18 +14,18 @@ public struct FormatTest: Codable {
     public var integer: Int?
     public var int32: Int?
     public var int64: Int64?
-    public var number: Double?
+    public var number: Double
     public var float: Float?
     public var double: Double?
     public var string: String?
-    public var byte: Data?
+    public var byte: Data
     public var binary: URL?
-    public var date: Date?
+    public var date: Date
     public var dateTime: Date?
     public var uuid: UUID?
-    public var password: String?
+    public var password: String
 
-    public init(integer: Int?, int32: Int?, int64: Int64?, number: Double?, float: Float?, double: Double?, string: String?, byte: Data?, binary: URL?, date: Date?, dateTime: Date?, uuid: UUID?, password: String?) {
+    public init(integer: Int?, int32: Int?, int64: Int64?, number: Double, float: Float?, double: Double?, string: String?, byte: Data, binary: URL?, date: Date, dateTime: Date?, uuid: UUID?, password: String) {
         self.integer = integer
         self.int32 = int32
         self.int64 = int64
diff --git a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Name.swift b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Name.swift
index bd7ad7ee6f78..cc165d767d91 100644
--- a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Name.swift
+++ b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Name.swift
@@ -12,12 +12,12 @@ import Foundation
 
 public struct Name: Codable {
 
-    public var name: Int?
+    public var name: Int
     public var snakeCase: Int?
     public var property: String?
     public var _123number: Int?
 
-    public init(name: Int?, snakeCase: Int?, property: String?, _123number: Int?) {
+    public init(name: Int, snakeCase: Int?, property: String?, _123number: Int?) {
         self.name = name
         self.snakeCase = snakeCase
         self.property = property
diff --git a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Pet.swift b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Pet.swift
index 533e1b861902..3773bf53317e 100644
--- a/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Pet.swift
+++ b/samples/client/petstore/swift4/unwrapRequired/PetstoreClient/Classes/OpenAPIs/Models/Pet.swift
@@ -18,13 +18,13 @@ public struct Pet: Codable {
     }
     public var _id: Int64?
     public var category: Category?
-    public var name: String?
-    public var photoUrls: [String]?
+    public var name: String
+    public var photoUrls: [String]
     public var tags: [Tag]?
     /** pet status in the store */
     public var status: Status?
 
-    public init(_id: Int64?, category: Category?, name: String?, photoUrls: [String]?, tags: [Tag]?, status: Status?) {
+    public init(_id: Int64?, category: Category?, name: String, photoUrls: [String], tags: [Tag]?, status: Status?) {
         self._id = _id
         self.category = category
         self.name = name
diff --git a/samples/client/test/swift4/default/.openapi-generator/VERSION b/samples/client/test/swift4/default/.openapi-generator/VERSION
index afa636560641..94ae9ee1fa8e 100644
--- a/samples/client/test/swift4/default/.openapi-generator/VERSION
+++ b/samples/client/test/swift4/default/.openapi-generator/VERSION
@@ -1 +1 @@
-4.0.0-SNAPSHOT
\ No newline at end of file
+4.0.0-SNAPSHOT