diff --git a/modules/openapi-generator/src/main/resources/go/model_simple.mustache b/modules/openapi-generator/src/main/resources/go/model_simple.mustache
index d634c704a34b..84c8b3a9e7ca 100644
--- a/modules/openapi-generator/src/main/resources/go/model_simple.mustache
+++ b/modules/openapi-generator/src/main/resources/go/model_simple.mustache
@@ -404,10 +404,14 @@ func (o *{{{classname}}}) UnmarshalJSON(bytes []byte) (err error) {
 {{#isMap}}
 	var{{{classname}}} := _{{{classname}}}{}
 
-	if err = json.Unmarshal(bytes, &var{{{classname}}}); err == nil {
-		*o = {{{classname}}}(var{{{classname}}})
+	err = json.Unmarshal(bytes, &var{{{classname}}})
+
+	if err != nil {
+		return err
 	}
 
+	*o = {{{classname}}}(var{{{classname}}})
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
@@ -423,10 +427,14 @@ func (o *{{{classname}}}) UnmarshalJSON(bytes []byte) (err error) {
 {{^parent}}
 	var{{{classname}}} := _{{{classname}}}{}
 
-	if err = json.Unmarshal(bytes, &var{{{classname}}}); err == nil {
-		*o = {{{classname}}}(var{{{classname}}})
+	err = json.Unmarshal(bytes, &var{{{classname}}})
+
+	if err != nil {
+		return err
 	}
 
+	*o = {{{classname}}}(var{{{classname}}})
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/client/petstore/go/go-petstore/model_additional_properties_any_type.go b/samples/client/petstore/go/go-petstore/model_additional_properties_any_type.go
index eadf2a95994a..880f95e954ab 100644
--- a/samples/client/petstore/go/go-petstore/model_additional_properties_any_type.go
+++ b/samples/client/petstore/go/go-petstore/model_additional_properties_any_type.go
@@ -98,10 +98,14 @@ func (o AdditionalPropertiesAnyType) ToMap() (map[string]interface{}, error) {
 func (o *AdditionalPropertiesAnyType) UnmarshalJSON(bytes []byte) (err error) {
 	varAdditionalPropertiesAnyType := _AdditionalPropertiesAnyType{}
 
-	if err = json.Unmarshal(bytes, &varAdditionalPropertiesAnyType); err == nil {
-		*o = AdditionalPropertiesAnyType(varAdditionalPropertiesAnyType)
+	err = json.Unmarshal(bytes, &varAdditionalPropertiesAnyType)
+
+	if err != nil {
+		return err
 	}
 
+	*o = AdditionalPropertiesAnyType(varAdditionalPropertiesAnyType)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/client/petstore/go/go-petstore/model_additional_properties_array.go b/samples/client/petstore/go/go-petstore/model_additional_properties_array.go
index f2527113454e..22c59ee9a613 100644
--- a/samples/client/petstore/go/go-petstore/model_additional_properties_array.go
+++ b/samples/client/petstore/go/go-petstore/model_additional_properties_array.go
@@ -98,10 +98,14 @@ func (o AdditionalPropertiesArray) ToMap() (map[string]interface{}, error) {
 func (o *AdditionalPropertiesArray) UnmarshalJSON(bytes []byte) (err error) {
 	varAdditionalPropertiesArray := _AdditionalPropertiesArray{}
 
-	if err = json.Unmarshal(bytes, &varAdditionalPropertiesArray); err == nil {
-		*o = AdditionalPropertiesArray(varAdditionalPropertiesArray)
+	err = json.Unmarshal(bytes, &varAdditionalPropertiesArray)
+
+	if err != nil {
+		return err
 	}
 
+	*o = AdditionalPropertiesArray(varAdditionalPropertiesArray)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/client/petstore/go/go-petstore/model_additional_properties_boolean.go b/samples/client/petstore/go/go-petstore/model_additional_properties_boolean.go
index c1401d929123..e898485760ab 100644
--- a/samples/client/petstore/go/go-petstore/model_additional_properties_boolean.go
+++ b/samples/client/petstore/go/go-petstore/model_additional_properties_boolean.go
@@ -98,10 +98,14 @@ func (o AdditionalPropertiesBoolean) ToMap() (map[string]interface{}, error) {
 func (o *AdditionalPropertiesBoolean) UnmarshalJSON(bytes []byte) (err error) {
 	varAdditionalPropertiesBoolean := _AdditionalPropertiesBoolean{}
 
-	if err = json.Unmarshal(bytes, &varAdditionalPropertiesBoolean); err == nil {
-		*o = AdditionalPropertiesBoolean(varAdditionalPropertiesBoolean)
+	err = json.Unmarshal(bytes, &varAdditionalPropertiesBoolean)
+
+	if err != nil {
+		return err
 	}
 
+	*o = AdditionalPropertiesBoolean(varAdditionalPropertiesBoolean)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/client/petstore/go/go-petstore/model_additional_properties_integer.go b/samples/client/petstore/go/go-petstore/model_additional_properties_integer.go
index 0147d6eaf856..af609f1474c0 100644
--- a/samples/client/petstore/go/go-petstore/model_additional_properties_integer.go
+++ b/samples/client/petstore/go/go-petstore/model_additional_properties_integer.go
@@ -98,10 +98,14 @@ func (o AdditionalPropertiesInteger) ToMap() (map[string]interface{}, error) {
 func (o *AdditionalPropertiesInteger) UnmarshalJSON(bytes []byte) (err error) {
 	varAdditionalPropertiesInteger := _AdditionalPropertiesInteger{}
 
-	if err = json.Unmarshal(bytes, &varAdditionalPropertiesInteger); err == nil {
-		*o = AdditionalPropertiesInteger(varAdditionalPropertiesInteger)
+	err = json.Unmarshal(bytes, &varAdditionalPropertiesInteger)
+
+	if err != nil {
+		return err
 	}
 
+	*o = AdditionalPropertiesInteger(varAdditionalPropertiesInteger)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/client/petstore/go/go-petstore/model_additional_properties_number.go b/samples/client/petstore/go/go-petstore/model_additional_properties_number.go
index 85b3663bf4cf..f3eb23fc4560 100644
--- a/samples/client/petstore/go/go-petstore/model_additional_properties_number.go
+++ b/samples/client/petstore/go/go-petstore/model_additional_properties_number.go
@@ -98,10 +98,14 @@ func (o AdditionalPropertiesNumber) ToMap() (map[string]interface{}, error) {
 func (o *AdditionalPropertiesNumber) UnmarshalJSON(bytes []byte) (err error) {
 	varAdditionalPropertiesNumber := _AdditionalPropertiesNumber{}
 
-	if err = json.Unmarshal(bytes, &varAdditionalPropertiesNumber); err == nil {
-		*o = AdditionalPropertiesNumber(varAdditionalPropertiesNumber)
+	err = json.Unmarshal(bytes, &varAdditionalPropertiesNumber)
+
+	if err != nil {
+		return err
 	}
 
+	*o = AdditionalPropertiesNumber(varAdditionalPropertiesNumber)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/client/petstore/go/go-petstore/model_additional_properties_object.go b/samples/client/petstore/go/go-petstore/model_additional_properties_object.go
index 7132cbe61bc4..d0730dc7f53d 100644
--- a/samples/client/petstore/go/go-petstore/model_additional_properties_object.go
+++ b/samples/client/petstore/go/go-petstore/model_additional_properties_object.go
@@ -98,10 +98,14 @@ func (o AdditionalPropertiesObject) ToMap() (map[string]interface{}, error) {
 func (o *AdditionalPropertiesObject) UnmarshalJSON(bytes []byte) (err error) {
 	varAdditionalPropertiesObject := _AdditionalPropertiesObject{}
 
-	if err = json.Unmarshal(bytes, &varAdditionalPropertiesObject); err == nil {
-		*o = AdditionalPropertiesObject(varAdditionalPropertiesObject)
+	err = json.Unmarshal(bytes, &varAdditionalPropertiesObject)
+
+	if err != nil {
+		return err
 	}
 
+	*o = AdditionalPropertiesObject(varAdditionalPropertiesObject)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/client/petstore/go/go-petstore/model_additional_properties_string.go b/samples/client/petstore/go/go-petstore/model_additional_properties_string.go
index 70882312adfe..acfc3440092f 100644
--- a/samples/client/petstore/go/go-petstore/model_additional_properties_string.go
+++ b/samples/client/petstore/go/go-petstore/model_additional_properties_string.go
@@ -98,10 +98,14 @@ func (o AdditionalPropertiesString) ToMap() (map[string]interface{}, error) {
 func (o *AdditionalPropertiesString) UnmarshalJSON(bytes []byte) (err error) {
 	varAdditionalPropertiesString := _AdditionalPropertiesString{}
 
-	if err = json.Unmarshal(bytes, &varAdditionalPropertiesString); err == nil {
-		*o = AdditionalPropertiesString(varAdditionalPropertiesString)
+	err = json.Unmarshal(bytes, &varAdditionalPropertiesString)
+
+	if err != nil {
+		return err
 	}
 
+	*o = AdditionalPropertiesString(varAdditionalPropertiesString)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_200_response.go b/samples/openapi3/client/petstore/go/go-petstore/model_200_response.go
index 68a402cba163..2bf31c269bb4 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_200_response.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_200_response.go
@@ -134,10 +134,14 @@ func (o Model200Response) ToMap() (map[string]interface{}, error) {
 func (o *Model200Response) UnmarshalJSON(bytes []byte) (err error) {
 	varModel200Response := _Model200Response{}
 
-	if err = json.Unmarshal(bytes, &varModel200Response); err == nil {
-		*o = Model200Response(varModel200Response)
+	err = json.Unmarshal(bytes, &varModel200Response)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Model200Response(varModel200Response)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model__foo_get_default_response.go b/samples/openapi3/client/petstore/go/go-petstore/model__foo_get_default_response.go
index 131bc4726e50..3e64a6b310ca 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model__foo_get_default_response.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model__foo_get_default_response.go
@@ -98,10 +98,14 @@ func (o FooGetDefaultResponse) ToMap() (map[string]interface{}, error) {
 func (o *FooGetDefaultResponse) UnmarshalJSON(bytes []byte) (err error) {
 	varFooGetDefaultResponse := _FooGetDefaultResponse{}
 
-	if err = json.Unmarshal(bytes, &varFooGetDefaultResponse); err == nil {
-		*o = FooGetDefaultResponse(varFooGetDefaultResponse)
+	err = json.Unmarshal(bytes, &varFooGetDefaultResponse)
+
+	if err != nil {
+		return err
 	}
 
+	*o = FooGetDefaultResponse(varFooGetDefaultResponse)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model__special_model_name_.go b/samples/openapi3/client/petstore/go/go-petstore/model__special_model_name_.go
index 55f423140575..0509ff5da5d8 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model__special_model_name_.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model__special_model_name_.go
@@ -98,10 +98,14 @@ func (o SpecialModelName) ToMap() (map[string]interface{}, error) {
 func (o *SpecialModelName) UnmarshalJSON(bytes []byte) (err error) {
 	varSpecialModelName := _SpecialModelName{}
 
-	if err = json.Unmarshal(bytes, &varSpecialModelName); err == nil {
-		*o = SpecialModelName(varSpecialModelName)
+	err = json.Unmarshal(bytes, &varSpecialModelName)
+
+	if err != nil {
+		return err
 	}
 
+	*o = SpecialModelName(varSpecialModelName)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_additional_properties_class.go b/samples/openapi3/client/petstore/go/go-petstore/model_additional_properties_class.go
index bf906f2224ba..d9210014d80d 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_additional_properties_class.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_additional_properties_class.go
@@ -134,10 +134,14 @@ func (o AdditionalPropertiesClass) ToMap() (map[string]interface{}, error) {
 func (o *AdditionalPropertiesClass) UnmarshalJSON(bytes []byte) (err error) {
 	varAdditionalPropertiesClass := _AdditionalPropertiesClass{}
 
-	if err = json.Unmarshal(bytes, &varAdditionalPropertiesClass); err == nil {
-		*o = AdditionalPropertiesClass(varAdditionalPropertiesClass)
+	err = json.Unmarshal(bytes, &varAdditionalPropertiesClass)
+
+	if err != nil {
+		return err
 	}
 
+	*o = AdditionalPropertiesClass(varAdditionalPropertiesClass)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_all_of_primitive_types.go b/samples/openapi3/client/petstore/go/go-petstore/model_all_of_primitive_types.go
index 825944aeadc2..8c6f26889502 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_all_of_primitive_types.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_all_of_primitive_types.go
@@ -99,10 +99,14 @@ func (o AllOfPrimitiveTypes) ToMap() (map[string]interface{}, error) {
 func (o *AllOfPrimitiveTypes) UnmarshalJSON(bytes []byte) (err error) {
 	varAllOfPrimitiveTypes := _AllOfPrimitiveTypes{}
 
-	if err = json.Unmarshal(bytes, &varAllOfPrimitiveTypes); err == nil {
-		*o = AllOfPrimitiveTypes(varAllOfPrimitiveTypes)
+	err = json.Unmarshal(bytes, &varAllOfPrimitiveTypes)
+
+	if err != nil {
+		return err
 	}
 
+	*o = AllOfPrimitiveTypes(varAllOfPrimitiveTypes)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_animal.go b/samples/openapi3/client/petstore/go/go-petstore/model_animal.go
index 5b8b9b9f0420..c01aa9aeadc2 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_animal.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_animal.go
@@ -129,10 +129,14 @@ func (o Animal) ToMap() (map[string]interface{}, error) {
 func (o *Animal) UnmarshalJSON(bytes []byte) (err error) {
 	varAnimal := _Animal{}
 
-	if err = json.Unmarshal(bytes, &varAnimal); err == nil {
-		*o = Animal(varAnimal)
+	err = json.Unmarshal(bytes, &varAnimal)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Animal(varAnimal)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_api_response.go b/samples/openapi3/client/petstore/go/go-petstore/model_api_response.go
index 699ca7d52f63..c8d0d91baabe 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_api_response.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_api_response.go
@@ -170,10 +170,14 @@ func (o ApiResponse) ToMap() (map[string]interface{}, error) {
 func (o *ApiResponse) UnmarshalJSON(bytes []byte) (err error) {
 	varApiResponse := _ApiResponse{}
 
-	if err = json.Unmarshal(bytes, &varApiResponse); err == nil {
-		*o = ApiResponse(varApiResponse)
+	err = json.Unmarshal(bytes, &varApiResponse)
+
+	if err != nil {
+		return err
 	}
 
+	*o = ApiResponse(varApiResponse)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_apple.go b/samples/openapi3/client/petstore/go/go-petstore/model_apple.go
index 43082aa35b6f..19df0b7b57b1 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_apple.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_apple.go
@@ -98,10 +98,14 @@ func (o Apple) ToMap() (map[string]interface{}, error) {
 func (o *Apple) UnmarshalJSON(bytes []byte) (err error) {
 	varApple := _Apple{}
 
-	if err = json.Unmarshal(bytes, &varApple); err == nil {
-		*o = Apple(varApple)
+	err = json.Unmarshal(bytes, &varApple)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Apple(varApple)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_apple_req.go b/samples/openapi3/client/petstore/go/go-petstore/model_apple_req.go
index 6e58309aa40b..23fa5ed2867b 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_apple_req.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_apple_req.go
@@ -125,10 +125,14 @@ func (o AppleReq) ToMap() (map[string]interface{}, error) {
 func (o *AppleReq) UnmarshalJSON(bytes []byte) (err error) {
 	varAppleReq := _AppleReq{}
 
-	if err = json.Unmarshal(bytes, &varAppleReq); err == nil {
-		*o = AppleReq(varAppleReq)
+	err = json.Unmarshal(bytes, &varAppleReq)
+
+	if err != nil {
+		return err
 	}
 
+	*o = AppleReq(varAppleReq)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_array_of_array_of_number_only.go b/samples/openapi3/client/petstore/go/go-petstore/model_array_of_array_of_number_only.go
index 9f84133a4ae1..6d4c67f246e2 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_array_of_array_of_number_only.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_array_of_array_of_number_only.go
@@ -98,10 +98,14 @@ func (o ArrayOfArrayOfNumberOnly) ToMap() (map[string]interface{}, error) {
 func (o *ArrayOfArrayOfNumberOnly) UnmarshalJSON(bytes []byte) (err error) {
 	varArrayOfArrayOfNumberOnly := _ArrayOfArrayOfNumberOnly{}
 
-	if err = json.Unmarshal(bytes, &varArrayOfArrayOfNumberOnly); err == nil {
-		*o = ArrayOfArrayOfNumberOnly(varArrayOfArrayOfNumberOnly)
+	err = json.Unmarshal(bytes, &varArrayOfArrayOfNumberOnly)
+
+	if err != nil {
+		return err
 	}
 
+	*o = ArrayOfArrayOfNumberOnly(varArrayOfArrayOfNumberOnly)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_array_of_number_only.go b/samples/openapi3/client/petstore/go/go-petstore/model_array_of_number_only.go
index e3ff1e6c56b8..d45cec963658 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_array_of_number_only.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_array_of_number_only.go
@@ -98,10 +98,14 @@ func (o ArrayOfNumberOnly) ToMap() (map[string]interface{}, error) {
 func (o *ArrayOfNumberOnly) UnmarshalJSON(bytes []byte) (err error) {
 	varArrayOfNumberOnly := _ArrayOfNumberOnly{}
 
-	if err = json.Unmarshal(bytes, &varArrayOfNumberOnly); err == nil {
-		*o = ArrayOfNumberOnly(varArrayOfNumberOnly)
+	err = json.Unmarshal(bytes, &varArrayOfNumberOnly)
+
+	if err != nil {
+		return err
 	}
 
+	*o = ArrayOfNumberOnly(varArrayOfNumberOnly)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_array_test_.go b/samples/openapi3/client/petstore/go/go-petstore/model_array_test_.go
index 5d97f8623397..2851c2f46843 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_array_test_.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_array_test_.go
@@ -170,10 +170,14 @@ func (o ArrayTest) ToMap() (map[string]interface{}, error) {
 func (o *ArrayTest) UnmarshalJSON(bytes []byte) (err error) {
 	varArrayTest := _ArrayTest{}
 
-	if err = json.Unmarshal(bytes, &varArrayTest); err == nil {
-		*o = ArrayTest(varArrayTest)
+	err = json.Unmarshal(bytes, &varArrayTest)
+
+	if err != nil {
+		return err
 	}
 
+	*o = ArrayTest(varArrayTest)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_banana.go b/samples/openapi3/client/petstore/go/go-petstore/model_banana.go
index 2a6f5d4d2624..4d757fbf9925 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_banana.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_banana.go
@@ -98,10 +98,14 @@ func (o Banana) ToMap() (map[string]interface{}, error) {
 func (o *Banana) UnmarshalJSON(bytes []byte) (err error) {
 	varBanana := _Banana{}
 
-	if err = json.Unmarshal(bytes, &varBanana); err == nil {
-		*o = Banana(varBanana)
+	err = json.Unmarshal(bytes, &varBanana)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Banana(varBanana)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_banana_req.go b/samples/openapi3/client/petstore/go/go-petstore/model_banana_req.go
index cb1045513e7b..5d5923fc5a7c 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_banana_req.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_banana_req.go
@@ -125,10 +125,14 @@ func (o BananaReq) ToMap() (map[string]interface{}, error) {
 func (o *BananaReq) UnmarshalJSON(bytes []byte) (err error) {
 	varBananaReq := _BananaReq{}
 
-	if err = json.Unmarshal(bytes, &varBananaReq); err == nil {
-		*o = BananaReq(varBananaReq)
+	err = json.Unmarshal(bytes, &varBananaReq)
+
+	if err != nil {
+		return err
 	}
 
+	*o = BananaReq(varBananaReq)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_capitalization.go b/samples/openapi3/client/petstore/go/go-petstore/model_capitalization.go
index 06a8833a2fbf..8b09f0d813e4 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_capitalization.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_capitalization.go
@@ -279,10 +279,14 @@ func (o Capitalization) ToMap() (map[string]interface{}, error) {
 func (o *Capitalization) UnmarshalJSON(bytes []byte) (err error) {
 	varCapitalization := _Capitalization{}
 
-	if err = json.Unmarshal(bytes, &varCapitalization); err == nil {
-		*o = Capitalization(varCapitalization)
+	err = json.Unmarshal(bytes, &varCapitalization)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Capitalization(varCapitalization)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_category.go b/samples/openapi3/client/petstore/go/go-petstore/model_category.go
index 6275a2967e93..bd4d6815e72e 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_category.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_category.go
@@ -127,10 +127,14 @@ func (o Category) ToMap() (map[string]interface{}, error) {
 func (o *Category) UnmarshalJSON(bytes []byte) (err error) {
 	varCategory := _Category{}
 
-	if err = json.Unmarshal(bytes, &varCategory); err == nil {
-		*o = Category(varCategory)
+	err = json.Unmarshal(bytes, &varCategory)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Category(varCategory)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_class_model.go b/samples/openapi3/client/petstore/go/go-petstore/model_class_model.go
index 0f01c8201721..72fe2596231c 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_class_model.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_class_model.go
@@ -98,10 +98,14 @@ func (o ClassModel) ToMap() (map[string]interface{}, error) {
 func (o *ClassModel) UnmarshalJSON(bytes []byte) (err error) {
 	varClassModel := _ClassModel{}
 
-	if err = json.Unmarshal(bytes, &varClassModel); err == nil {
-		*o = ClassModel(varClassModel)
+	err = json.Unmarshal(bytes, &varClassModel)
+
+	if err != nil {
+		return err
 	}
 
+	*o = ClassModel(varClassModel)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_client.go b/samples/openapi3/client/petstore/go/go-petstore/model_client.go
index f034a9f91f22..e635b0546e07 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_client.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_client.go
@@ -98,10 +98,14 @@ func (o Client) ToMap() (map[string]interface{}, error) {
 func (o *Client) UnmarshalJSON(bytes []byte) (err error) {
 	varClient := _Client{}
 
-	if err = json.Unmarshal(bytes, &varClient); err == nil {
-		*o = Client(varClient)
+	err = json.Unmarshal(bytes, &varClient)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Client(varClient)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_duplicated_prop_parent.go b/samples/openapi3/client/petstore/go/go-petstore/model_duplicated_prop_parent.go
index 1c8ed0909f66..bb2e2132e122 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_duplicated_prop_parent.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_duplicated_prop_parent.go
@@ -90,10 +90,14 @@ func (o DuplicatedPropParent) ToMap() (map[string]interface{}, error) {
 func (o *DuplicatedPropParent) UnmarshalJSON(bytes []byte) (err error) {
 	varDuplicatedPropParent := _DuplicatedPropParent{}
 
-	if err = json.Unmarshal(bytes, &varDuplicatedPropParent); err == nil {
-		*o = DuplicatedPropParent(varDuplicatedPropParent)
+	err = json.Unmarshal(bytes, &varDuplicatedPropParent)
+
+	if err != nil {
+		return err
 	}
 
+	*o = DuplicatedPropParent(varDuplicatedPropParent)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_enum_arrays.go b/samples/openapi3/client/petstore/go/go-petstore/model_enum_arrays.go
index 9a16611ca047..cbb59df3be01 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_enum_arrays.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_enum_arrays.go
@@ -134,10 +134,14 @@ func (o EnumArrays) ToMap() (map[string]interface{}, error) {
 func (o *EnumArrays) UnmarshalJSON(bytes []byte) (err error) {
 	varEnumArrays := _EnumArrays{}
 
-	if err = json.Unmarshal(bytes, &varEnumArrays); err == nil {
-		*o = EnumArrays(varEnumArrays)
+	err = json.Unmarshal(bytes, &varEnumArrays)
+
+	if err != nil {
+		return err
 	}
 
+	*o = EnumArrays(varEnumArrays)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_enum_test_.go b/samples/openapi3/client/petstore/go/go-petstore/model_enum_test_.go
index 14202318657c..eb00c70e14f6 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_enum_test_.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_enum_test_.go
@@ -359,10 +359,14 @@ func (o EnumTest) ToMap() (map[string]interface{}, error) {
 func (o *EnumTest) UnmarshalJSON(bytes []byte) (err error) {
 	varEnumTest := _EnumTest{}
 
-	if err = json.Unmarshal(bytes, &varEnumTest); err == nil {
-		*o = EnumTest(varEnumTest)
+	err = json.Unmarshal(bytes, &varEnumTest)
+
+	if err != nil {
+		return err
 	}
 
+	*o = EnumTest(varEnumTest)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_file.go b/samples/openapi3/client/petstore/go/go-petstore/model_file.go
index 631cd8ee96b2..bf26cb96bf35 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_file.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_file.go
@@ -99,10 +99,14 @@ func (o File) ToMap() (map[string]interface{}, error) {
 func (o *File) UnmarshalJSON(bytes []byte) (err error) {
 	varFile := _File{}
 
-	if err = json.Unmarshal(bytes, &varFile); err == nil {
-		*o = File(varFile)
+	err = json.Unmarshal(bytes, &varFile)
+
+	if err != nil {
+		return err
 	}
 
+	*o = File(varFile)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_file_schema_test_class.go b/samples/openapi3/client/petstore/go/go-petstore/model_file_schema_test_class.go
index d35771316bbf..ab98b53cba46 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_file_schema_test_class.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_file_schema_test_class.go
@@ -134,10 +134,14 @@ func (o FileSchemaTestClass) ToMap() (map[string]interface{}, error) {
 func (o *FileSchemaTestClass) UnmarshalJSON(bytes []byte) (err error) {
 	varFileSchemaTestClass := _FileSchemaTestClass{}
 
-	if err = json.Unmarshal(bytes, &varFileSchemaTestClass); err == nil {
-		*o = FileSchemaTestClass(varFileSchemaTestClass)
+	err = json.Unmarshal(bytes, &varFileSchemaTestClass)
+
+	if err != nil {
+		return err
 	}
 
+	*o = FileSchemaTestClass(varFileSchemaTestClass)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_foo.go b/samples/openapi3/client/petstore/go/go-petstore/model_foo.go
index 930080a69eb4..76e88bfaa2e2 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_foo.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_foo.go
@@ -102,10 +102,14 @@ func (o Foo) ToMap() (map[string]interface{}, error) {
 func (o *Foo) UnmarshalJSON(bytes []byte) (err error) {
 	varFoo := _Foo{}
 
-	if err = json.Unmarshal(bytes, &varFoo); err == nil {
-		*o = Foo(varFoo)
+	err = json.Unmarshal(bytes, &varFoo)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Foo(varFoo)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_format_test_.go b/samples/openapi3/client/petstore/go/go-petstore/model_format_test_.go
index b887e12ec737..499ceba4acb0 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_format_test_.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_format_test_.go
@@ -570,10 +570,14 @@ func (o FormatTest) ToMap() (map[string]interface{}, error) {
 func (o *FormatTest) UnmarshalJSON(bytes []byte) (err error) {
 	varFormatTest := _FormatTest{}
 
-	if err = json.Unmarshal(bytes, &varFormatTest); err == nil {
-		*o = FormatTest(varFormatTest)
+	err = json.Unmarshal(bytes, &varFormatTest)
+
+	if err != nil {
+		return err
 	}
 
+	*o = FormatTest(varFormatTest)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_has_only_read_only.go b/samples/openapi3/client/petstore/go/go-petstore/model_has_only_read_only.go
index 7f37585fa2e0..c7f8236ee236 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_has_only_read_only.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_has_only_read_only.go
@@ -134,10 +134,14 @@ func (o HasOnlyReadOnly) ToMap() (map[string]interface{}, error) {
 func (o *HasOnlyReadOnly) UnmarshalJSON(bytes []byte) (err error) {
 	varHasOnlyReadOnly := _HasOnlyReadOnly{}
 
-	if err = json.Unmarshal(bytes, &varHasOnlyReadOnly); err == nil {
-		*o = HasOnlyReadOnly(varHasOnlyReadOnly)
+	err = json.Unmarshal(bytes, &varHasOnlyReadOnly)
+
+	if err != nil {
+		return err
 	}
 
+	*o = HasOnlyReadOnly(varHasOnlyReadOnly)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_health_check_result.go b/samples/openapi3/client/petstore/go/go-petstore/model_health_check_result.go
index c3498f9e9f8a..3617d9b3f8b7 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_health_check_result.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_health_check_result.go
@@ -108,10 +108,14 @@ func (o HealthCheckResult) ToMap() (map[string]interface{}, error) {
 func (o *HealthCheckResult) UnmarshalJSON(bytes []byte) (err error) {
 	varHealthCheckResult := _HealthCheckResult{}
 
-	if err = json.Unmarshal(bytes, &varHealthCheckResult); err == nil {
-		*o = HealthCheckResult(varHealthCheckResult)
+	err = json.Unmarshal(bytes, &varHealthCheckResult)
+
+	if err != nil {
+		return err
 	}
 
+	*o = HealthCheckResult(varHealthCheckResult)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_list.go b/samples/openapi3/client/petstore/go/go-petstore/model_list.go
index 77017d73bc0c..8af38e91ef3b 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_list.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_list.go
@@ -98,10 +98,14 @@ func (o List) ToMap() (map[string]interface{}, error) {
 func (o *List) UnmarshalJSON(bytes []byte) (err error) {
 	varList := _List{}
 
-	if err = json.Unmarshal(bytes, &varList); err == nil {
-		*o = List(varList)
+	err = json.Unmarshal(bytes, &varList)
+
+	if err != nil {
+		return err
 	}
 
+	*o = List(varList)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_map_of_file_test_.go b/samples/openapi3/client/petstore/go/go-petstore/model_map_of_file_test_.go
index e14eaaafe243..c86070564546 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_map_of_file_test_.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_map_of_file_test_.go
@@ -100,10 +100,14 @@ func (o MapOfFileTest) ToMap() (map[string]interface{}, error) {
 func (o *MapOfFileTest) UnmarshalJSON(bytes []byte) (err error) {
 	varMapOfFileTest := _MapOfFileTest{}
 
-	if err = json.Unmarshal(bytes, &varMapOfFileTest); err == nil {
-		*o = MapOfFileTest(varMapOfFileTest)
+	err = json.Unmarshal(bytes, &varMapOfFileTest)
+
+	if err != nil {
+		return err
 	}
 
+	*o = MapOfFileTest(varMapOfFileTest)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_map_test_.go b/samples/openapi3/client/petstore/go/go-petstore/model_map_test_.go
index bd512760a45f..f7fefb0c1036 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_map_test_.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_map_test_.go
@@ -206,10 +206,14 @@ func (o MapTest) ToMap() (map[string]interface{}, error) {
 func (o *MapTest) UnmarshalJSON(bytes []byte) (err error) {
 	varMapTest := _MapTest{}
 
-	if err = json.Unmarshal(bytes, &varMapTest); err == nil {
-		*o = MapTest(varMapTest)
+	err = json.Unmarshal(bytes, &varMapTest)
+
+	if err != nil {
+		return err
 	}
 
+	*o = MapTest(varMapTest)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_mixed_properties_and_additional_properties_class.go b/samples/openapi3/client/petstore/go/go-petstore/model_mixed_properties_and_additional_properties_class.go
index 4a65bb995733..8470ccb66320 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_mixed_properties_and_additional_properties_class.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_mixed_properties_and_additional_properties_class.go
@@ -171,10 +171,14 @@ func (o MixedPropertiesAndAdditionalPropertiesClass) ToMap() (map[string]interfa
 func (o *MixedPropertiesAndAdditionalPropertiesClass) UnmarshalJSON(bytes []byte) (err error) {
 	varMixedPropertiesAndAdditionalPropertiesClass := _MixedPropertiesAndAdditionalPropertiesClass{}
 
-	if err = json.Unmarshal(bytes, &varMixedPropertiesAndAdditionalPropertiesClass); err == nil {
-		*o = MixedPropertiesAndAdditionalPropertiesClass(varMixedPropertiesAndAdditionalPropertiesClass)
+	err = json.Unmarshal(bytes, &varMixedPropertiesAndAdditionalPropertiesClass)
+
+	if err != nil {
+		return err
 	}
 
+	*o = MixedPropertiesAndAdditionalPropertiesClass(varMixedPropertiesAndAdditionalPropertiesClass)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_name.go b/samples/openapi3/client/petstore/go/go-petstore/model_name.go
index 74b7b5deda0b..84a92878766a 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_name.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_name.go
@@ -197,10 +197,14 @@ func (o Name) ToMap() (map[string]interface{}, error) {
 func (o *Name) UnmarshalJSON(bytes []byte) (err error) {
 	varName := _Name{}
 
-	if err = json.Unmarshal(bytes, &varName); err == nil {
-		*o = Name(varName)
+	err = json.Unmarshal(bytes, &varName)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Name(varName)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_nullable_all_of.go b/samples/openapi3/client/petstore/go/go-petstore/model_nullable_all_of.go
index f9f10c7e5ff4..3f7029b787da 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_nullable_all_of.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_nullable_all_of.go
@@ -108,10 +108,14 @@ func (o NullableAllOf) ToMap() (map[string]interface{}, error) {
 func (o *NullableAllOf) UnmarshalJSON(bytes []byte) (err error) {
 	varNullableAllOf := _NullableAllOf{}
 
-	if err = json.Unmarshal(bytes, &varNullableAllOf); err == nil {
-		*o = NullableAllOf(varNullableAllOf)
+	err = json.Unmarshal(bytes, &varNullableAllOf)
+
+	if err != nil {
+		return err
 	}
 
+	*o = NullableAllOf(varNullableAllOf)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_nullable_all_of_child.go b/samples/openapi3/client/petstore/go/go-petstore/model_nullable_all_of_child.go
index 7b28b820f332..0aec0ac62550 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_nullable_all_of_child.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_nullable_all_of_child.go
@@ -98,10 +98,14 @@ func (o NullableAllOfChild) ToMap() (map[string]interface{}, error) {
 func (o *NullableAllOfChild) UnmarshalJSON(bytes []byte) (err error) {
 	varNullableAllOfChild := _NullableAllOfChild{}
 
-	if err = json.Unmarshal(bytes, &varNullableAllOfChild); err == nil {
-		*o = NullableAllOfChild(varNullableAllOfChild)
+	err = json.Unmarshal(bytes, &varNullableAllOfChild)
+
+	if err != nil {
+		return err
 	}
 
+	*o = NullableAllOfChild(varNullableAllOfChild)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_nullable_class.go b/samples/openapi3/client/petstore/go/go-petstore/model_nullable_class.go
index 580936cff216..a323a2e59524 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_nullable_class.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_nullable_class.go
@@ -563,10 +563,14 @@ func (o NullableClass) ToMap() (map[string]interface{}, error) {
 func (o *NullableClass) UnmarshalJSON(bytes []byte) (err error) {
 	varNullableClass := _NullableClass{}
 
-	if err = json.Unmarshal(bytes, &varNullableClass); err == nil {
-		*o = NullableClass(varNullableClass)
+	err = json.Unmarshal(bytes, &varNullableClass)
+
+	if err != nil {
+		return err
 	}
 
+	*o = NullableClass(varNullableClass)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_number_only.go b/samples/openapi3/client/petstore/go/go-petstore/model_number_only.go
index 36bd0c4b7a2b..95b416db196f 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_number_only.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_number_only.go
@@ -98,10 +98,14 @@ func (o NumberOnly) ToMap() (map[string]interface{}, error) {
 func (o *NumberOnly) UnmarshalJSON(bytes []byte) (err error) {
 	varNumberOnly := _NumberOnly{}
 
-	if err = json.Unmarshal(bytes, &varNumberOnly); err == nil {
-		*o = NumberOnly(varNumberOnly)
+	err = json.Unmarshal(bytes, &varNumberOnly)
+
+	if err != nil {
+		return err
 	}
 
+	*o = NumberOnly(varNumberOnly)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_one_of_primitive_type_child.go b/samples/openapi3/client/petstore/go/go-petstore/model_one_of_primitive_type_child.go
index 1c719015646d..1fa6693b43b3 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_one_of_primitive_type_child.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_one_of_primitive_type_child.go
@@ -98,10 +98,14 @@ func (o OneOfPrimitiveTypeChild) ToMap() (map[string]interface{}, error) {
 func (o *OneOfPrimitiveTypeChild) UnmarshalJSON(bytes []byte) (err error) {
 	varOneOfPrimitiveTypeChild := _OneOfPrimitiveTypeChild{}
 
-	if err = json.Unmarshal(bytes, &varOneOfPrimitiveTypeChild); err == nil {
-		*o = OneOfPrimitiveTypeChild(varOneOfPrimitiveTypeChild)
+	err = json.Unmarshal(bytes, &varOneOfPrimitiveTypeChild)
+
+	if err != nil {
+		return err
 	}
 
+	*o = OneOfPrimitiveTypeChild(varOneOfPrimitiveTypeChild)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_order.go b/samples/openapi3/client/petstore/go/go-petstore/model_order.go
index a4be8a04ee2a..15f139933399 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_order.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_order.go
@@ -284,10 +284,14 @@ func (o Order) ToMap() (map[string]interface{}, error) {
 func (o *Order) UnmarshalJSON(bytes []byte) (err error) {
 	varOrder := _Order{}
 
-	if err = json.Unmarshal(bytes, &varOrder); err == nil {
-		*o = Order(varOrder)
+	err = json.Unmarshal(bytes, &varOrder)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Order(varOrder)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_outer_composite.go b/samples/openapi3/client/petstore/go/go-petstore/model_outer_composite.go
index 74c5518557bb..279f46eeac46 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_outer_composite.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_outer_composite.go
@@ -170,10 +170,14 @@ func (o OuterComposite) ToMap() (map[string]interface{}, error) {
 func (o *OuterComposite) UnmarshalJSON(bytes []byte) (err error) {
 	varOuterComposite := _OuterComposite{}
 
-	if err = json.Unmarshal(bytes, &varOuterComposite); err == nil {
-		*o = OuterComposite(varOuterComposite)
+	err = json.Unmarshal(bytes, &varOuterComposite)
+
+	if err != nil {
+		return err
 	}
 
+	*o = OuterComposite(varOuterComposite)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_pet.go b/samples/openapi3/client/petstore/go/go-petstore/model_pet.go
index 156f6be2f76b..0f1ffe373e5b 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_pet.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_pet.go
@@ -265,10 +265,14 @@ func (o Pet) ToMap() (map[string]interface{}, error) {
 func (o *Pet) UnmarshalJSON(bytes []byte) (err error) {
 	varPet := _Pet{}
 
-	if err = json.Unmarshal(bytes, &varPet); err == nil {
-		*o = Pet(varPet)
+	err = json.Unmarshal(bytes, &varPet)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Pet(varPet)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_property_name_mapping.go b/samples/openapi3/client/petstore/go/go-petstore/model_property_name_mapping.go
index 058a55bd0b26..c621f708467d 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_property_name_mapping.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_property_name_mapping.go
@@ -206,10 +206,14 @@ func (o PropertyNameMapping) ToMap() (map[string]interface{}, error) {
 func (o *PropertyNameMapping) UnmarshalJSON(bytes []byte) (err error) {
 	varPropertyNameMapping := _PropertyNameMapping{}
 
-	if err = json.Unmarshal(bytes, &varPropertyNameMapping); err == nil {
-		*o = PropertyNameMapping(varPropertyNameMapping)
+	err = json.Unmarshal(bytes, &varPropertyNameMapping)
+
+	if err != nil {
+		return err
 	}
 
+	*o = PropertyNameMapping(varPropertyNameMapping)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_read_only_first.go b/samples/openapi3/client/petstore/go/go-petstore/model_read_only_first.go
index 6aa66a79f202..3b240abf82b7 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_read_only_first.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_read_only_first.go
@@ -134,10 +134,14 @@ func (o ReadOnlyFirst) ToMap() (map[string]interface{}, error) {
 func (o *ReadOnlyFirst) UnmarshalJSON(bytes []byte) (err error) {
 	varReadOnlyFirst := _ReadOnlyFirst{}
 
-	if err = json.Unmarshal(bytes, &varReadOnlyFirst); err == nil {
-		*o = ReadOnlyFirst(varReadOnlyFirst)
+	err = json.Unmarshal(bytes, &varReadOnlyFirst)
+
+	if err != nil {
+		return err
 	}
 
+	*o = ReadOnlyFirst(varReadOnlyFirst)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_read_only_with_default.go b/samples/openapi3/client/petstore/go/go-petstore/model_read_only_with_default.go
index 146b94ebc147..5bf6817a9c9b 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_read_only_with_default.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_read_only_with_default.go
@@ -326,10 +326,14 @@ func (o ReadOnlyWithDefault) ToMap() (map[string]interface{}, error) {
 func (o *ReadOnlyWithDefault) UnmarshalJSON(bytes []byte) (err error) {
 	varReadOnlyWithDefault := _ReadOnlyWithDefault{}
 
-	if err = json.Unmarshal(bytes, &varReadOnlyWithDefault); err == nil {
-		*o = ReadOnlyWithDefault(varReadOnlyWithDefault)
+	err = json.Unmarshal(bytes, &varReadOnlyWithDefault)
+
+	if err != nil {
+		return err
 	}
 
+	*o = ReadOnlyWithDefault(varReadOnlyWithDefault)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_return.go b/samples/openapi3/client/petstore/go/go-petstore/model_return.go
index e77f7e007925..991ccc4bd796 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_return.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_return.go
@@ -98,10 +98,14 @@ func (o Return) ToMap() (map[string]interface{}, error) {
 func (o *Return) UnmarshalJSON(bytes []byte) (err error) {
 	varReturn := _Return{}
 
-	if err = json.Unmarshal(bytes, &varReturn); err == nil {
-		*o = Return(varReturn)
+	err = json.Unmarshal(bytes, &varReturn)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Return(varReturn)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_tag.go b/samples/openapi3/client/petstore/go/go-petstore/model_tag.go
index f77bf7206b0c..822a5a12c015 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_tag.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_tag.go
@@ -134,10 +134,14 @@ func (o Tag) ToMap() (map[string]interface{}, error) {
 func (o *Tag) UnmarshalJSON(bytes []byte) (err error) {
 	varTag := _Tag{}
 
-	if err = json.Unmarshal(bytes, &varTag); err == nil {
-		*o = Tag(varTag)
+	err = json.Unmarshal(bytes, &varTag)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Tag(varTag)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_user.go b/samples/openapi3/client/petstore/go/go-petstore/model_user.go
index b884647d1be0..08a1961af341 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_user.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_user.go
@@ -502,10 +502,14 @@ func (o User) ToMap() (map[string]interface{}, error) {
 func (o *User) UnmarshalJSON(bytes []byte) (err error) {
 	varUser := _User{}
 
-	if err = json.Unmarshal(bytes, &varUser); err == nil {
-		*o = User(varUser)
+	err = json.Unmarshal(bytes, &varUser)
+
+	if err != nil {
+		return err
 	}
 
+	*o = User(varUser)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_whale.go b/samples/openapi3/client/petstore/go/go-petstore/model_whale.go
index 8ee96e3aea32..7e450a046cd9 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_whale.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_whale.go
@@ -161,10 +161,14 @@ func (o Whale) ToMap() (map[string]interface{}, error) {
 func (o *Whale) UnmarshalJSON(bytes []byte) (err error) {
 	varWhale := _Whale{}
 
-	if err = json.Unmarshal(bytes, &varWhale); err == nil {
-		*o = Whale(varWhale)
+	err = json.Unmarshal(bytes, &varWhale)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Whale(varWhale)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/model_zebra.go b/samples/openapi3/client/petstore/go/go-petstore/model_zebra.go
index 3349c9470cfc..01a0ae804d41 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/model_zebra.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/model_zebra.go
@@ -125,10 +125,14 @@ func (o Zebra) ToMap() (map[string]interface{}, error) {
 func (o *Zebra) UnmarshalJSON(bytes []byte) (err error) {
 	varZebra := _Zebra{}
 
-	if err = json.Unmarshal(bytes, &varZebra); err == nil {
-		*o = Zebra(varZebra)
+	err = json.Unmarshal(bytes, &varZebra)
+
+	if err != nil {
+		return err
 	}
 
+	*o = Zebra(varZebra)
+
 	additionalProperties := make(map[string]interface{})
 
 	if err = json.Unmarshal(bytes, &additionalProperties); err == nil {
diff --git a/samples/openapi3/client/petstore/go/store_api_test.go b/samples/openapi3/client/petstore/go/store_api_test.go
index d8d5834452bf..564117a2bf84 100644
--- a/samples/openapi3/client/petstore/go/store_api_test.go
+++ b/samples/openapi3/client/petstore/go/store_api_test.go
@@ -24,7 +24,7 @@ func TestPlaceOrder(t *testing.T) {
 		// Skip parsing time error due to error in Petstore Test Server
 		// https://github.com/OpenAPITools/openapi-generator/issues/1292
 		if regexp.
-			MustCompile(`^parsing time.+cannot parse "\+0000"" as "Z07:00"$`).
+			MustCompile(`as "Z07:00"$`).
 			MatchString(err.Error()) {
 			t.Log("Skipping error for parsing time with `+0000` UTC offset as Petstore Test Server does not return valid RFC 3339 datetime")
 		} else {