diff --git a/modules/openapi-generator/src/main/resources/go/client.mustache b/modules/openapi-generator/src/main/resources/go/client.mustache
index a6aec184854b..c4ef64ee2e0c 100644
--- a/modules/openapi-generator/src/main/resources/go/client.mustache
+++ b/modules/openapi-generator/src/main/resources/go/client.mustache
@@ -188,7 +188,7 @@ func (c *APIClient) prepareRequest(
 	}
 
 	// add form parameters and file if available.
-	if len(formParams) > 0 || (len(fileBytes) > 0 && fileName != "") {
+	if strings.HasPrefix(headerParams["Content-Type"], "multipart/form-data") && len(formParams) > 0 || (len(fileBytes) > 0 && fileName != "") {
 		if body != nil {
 			return nil, errors.New("Cannot specify postBody and multipart form at the same time.")
 		}
@@ -227,6 +227,16 @@ func (c *APIClient) prepareRequest(
 		w.Close()
 	}
 
+	if strings.HasPrefix(headerParams["Content-Type"], "application/x-www-form-urlencoded") && len(formParams) > 0 {
+		if body != nil {
+			return nil, errors.New("Cannot specify postBody and x-www-form-urlencoded form at the same time.")
+		}
+		body = &bytes.Buffer{}
+		body.WriteString(formParams.Encode())
+		// Set Content-Length
+		headerParams["Content-Length"] = fmt.Sprintf("%d", body.Len())
+	}
+
 	// Setup path and query parameters
 	url, err := url.Parse(path)
 	if err != nil {
@@ -469,4 +479,4 @@ func (e GenericOpenAPIError) Body() []byte {
 // Model returns the unpacked model of the error
 func (e GenericOpenAPIError) Model() interface{} {
 	return e.model
-}
\ No newline at end of file
+}
diff --git a/modules/openapi-generator/src/test/resources/2_0/petstore-security-test.yaml b/modules/openapi-generator/src/test/resources/2_0/petstore-security-test.yaml
index e63cb90e0a67..f1400ad8c638 100644
--- a/modules/openapi-generator/src/test/resources/2_0/petstore-security-test.yaml
+++ b/modules/openapi-generator/src/test/resources/2_0/petstore-security-test.yaml
@@ -36,7 +36,7 @@ paths:
       parameters:
         - name: test code inject */ ' " =end -- \r\n \n \r
           type: string
-          in: formData 
+          in: formData
           description: To test code injection */ ' " =end -- \r\n \n \r
       responses:
         '400':
diff --git a/samples/client/petstore-security-test/go/.openapi-generator/VERSION b/samples/client/petstore-security-test/go/.openapi-generator/VERSION
index 096bf47efe31..f4cb97d56ce2 100644
--- a/samples/client/petstore-security-test/go/.openapi-generator/VERSION
+++ b/samples/client/petstore-security-test/go/.openapi-generator/VERSION
@@ -1 +1 @@
-3.0.0-SNAPSHOT
\ No newline at end of file
+3.3.1-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore-security-test/go/README.md b/samples/client/petstore-security-test/go/README.md
index ea6e8af4f503..f94b342e3148 100644
--- a/samples/client/petstore-security-test/go/README.md
+++ b/samples/client/petstore-security-test/go/README.md
@@ -26,7 +26,7 @@ import "./openapi"
 
 ## Documentation for API Endpoints
 
-All URIs are relative to *petstore.swagger.io *_/ ' \" =end -- \\r\\n \\n \\r/v2 *_/ ' \" =end -- \\r\\n \\n \\r*
+All URIs are relative to *http://petstore.swagger.io *_/ ' \" =end -- \\r\\n \\n \\r/v2 *_/ ' \" =end -- \\r\\n \\n \\r*
 
 Class | Method | HTTP request | Description
 ------------ | ------------- | ------------- | -------------
diff --git a/samples/client/petstore-security-test/go/api/openapi.yaml b/samples/client/petstore-security-test/go/api/openapi.yaml
index 8ed2aa894f41..ad8c8ff7cf29 100644
--- a/samples/client/petstore-security-test/go/api/openapi.yaml
+++ b/samples/client/petstore-security-test/go/api/openapi.yaml
@@ -1,33 +1,31 @@
 openapi: 3.0.1
 info:
-  title: OpenAPI Petstore */ ' " =end -- \r\n \n \r
+  contact:
+    email: something@something.abc */ ' " =end -- \r\n \n \r
   description: "This spec is mainly for testing Petstore server and contains fake\
     \ endpoints, models. Please do not use this for any other purpose. Special characters:\
     \ \" \\  */ ' \" =end -- \r\n \n \r"
-  termsOfService: http://url.to/terms/ */ ' " =end -- \r\n \n \r
-  contact:
-    email: something@something.abc */ ' " =end -- \r\n \n \r
   license:
     name: Apache-2.0 */ ' " =end -- \r\n \n \r
     url: http://www.apache.org/licenses/LICENSE-2.0.html */ ' " =end -- \r\n \n \r
+  termsOfService: http://url.to/terms/ */ ' " =end -- \r\n \n \r
+  title: OpenAPI Petstore */ ' " =end -- \r\n \n \r
   version: 1.0.0 */ ' " =end -- \r\n \n \r
 externalDocs:
   description: Find out more about OpenAPI  */ ' " =end -- \r\n \n \r
   url: https://openapis.org
 servers:
-- url: petstore.swagger.io */ ' " =end -- \r\n \n \r/v2 */ ' " =end -- \r\n \n \r
+- url: //petstore.swagger.io */ ' " =end -- \r\n \n \r/v2 */ ' " =end -- \r\n \n \r
 tags:
-- name: fake
-  description: Everything about your Pets */ ' " =end -- \r\n \n \r
+- description: Everything about your Pets */ ' " =end -- \r\n \n \r
   externalDocs:
     description: Find out more */ ' " =end -- \r\n \n \r
     url: https://openapis.org
+  name: fake
 paths:
   /fake:
     put:
-      tags:
-      - fake
-      summary: To test code injection */ ' " =end -- \r\n \n \r
+      description: To test code injection */ ' " =end -- \r\n \n \r
       operationId: testCodeInject */ ' " =end -- \r\n \n \r
       requestBody:
         content:
@@ -35,40 +33,43 @@ paths:
             schema:
               properties:
                 test code inject */ ' " =end -- \r\n \n \r:
-                  type: string
                   description: To test code injection */ ' " =end -- \r\n \n \r
+                  type: string
           ? "*/ ' \" =end -- \r\n \n \r"
           : schema:
               properties:
                 test code inject */ ' " =end -- \r\n \n \r:
-                  type: string
                   description: To test code injection */ ' " =end -- \r\n \n \r
+                  type: string
       responses:
         400:
-          description: To test code injection */ ' " =end -- \r\n \n \r
           content: {}
+          description: To test code injection */ ' " =end -- \r\n \n \r
+      summary: To test code injection */ ' " =end -- \r\n \n \r
+      tags:
+      - fake
 components:
   schemas:
     Return:
-      type: object
+      description: Model for testing reserved words  */ ' " =end -- \r\n \n \r
       properties:
         return:
-          type: integer
           description: property description  */ ' " =end -- \r\n \n \r
           format: int32
-      description: Model for testing reserved words  */ ' " =end -- \r\n \n \r
+          type: integer
+      type: object
       xml:
         name: Return
   securitySchemes:
     petstore_auth:
-      type: oauth2
       flows:
         implicit:
           authorizationUrl: http://petstore.swagger.io/api/oauth/dialog
           scopes:
             write:pets: modify pets in your account  */ ' " =end -- \r\n \n \r
             read:pets: read your pets  */ ' " =end -- \r\n \n \r
+      type: oauth2
     api_key:
-      type: apiKey
-      name: api_key  */ ' " =end -- \r\n \n \r
       in: header
+      name: api_key  */ ' " =end -- \r\n \n \r
+      type: apiKey
diff --git a/samples/client/petstore-security-test/go/api_fake.go b/samples/client/petstore-security-test/go/api_fake.go
index c0668d851ef2..957fbf399523 100644
--- a/samples/client/petstore-security-test/go/api_fake.go
+++ b/samples/client/petstore-security-test/go/api_fake.go
@@ -16,6 +16,7 @@ import (
 	"net/http"
 	"net/url"
 	"strings"
+	"github.com/antihax/optional"
 )
 
 // Linger please
@@ -25,23 +26,25 @@ var (
 
 type FakeApiService service
 
-/* 
-FakeApiService To test code injection *_/ ' \" =end -- \\r\\n \\n \\r
+/*
+FakeApiService To test code injection *_/ ' \" =end -- \\r\\n \\n \\r
+To test code injection *_/ ' \" =end -- \\r\\n \\n \\r
  * @param ctx context.Context - for authentication, logging, cancellation, deadlines, tracing, etc. Passed from http.Request or context.Background().
  * @param optional nil or *TestCodeInjectEndRnNROpts - Optional Parameters:
- * @param "UNKNOWNBASETYPE" (optional.Interface of interface{}) - 
+ * @param "UNKNOWNBASETYPE" (optional.Interface of UNKNOWN_BASE_TYPE) - 
 */
 
 type TestCodeInjectEndRnNROpts struct {
-    UNKNOWNBASETYPE optional.Interface
+	UNKNOWNBASETYPE optional.Interface
 }
 
 func (a *FakeApiService) TestCodeInjectEndRnNR(ctx context.Context, localVarOptionals *TestCodeInjectEndRnNROpts) (*http.Response, error) {
 	var (
-		localVarHttpMethod = strings.ToUpper("Put")
-		localVarPostBody   interface{}
-		localVarFileName   string
-		localVarFileBytes  []byte
+		localVarHttpMethod   = strings.ToUpper("Put")
+		localVarPostBody     interface{}
+		localVarFormFileName string
+		localVarFileName     string
+		localVarFileBytes    []byte
 	)
 
 	// create path and map variables
@@ -70,14 +73,14 @@ func (a *FakeApiService) TestCodeInjectEndRnNR(ctx context.Context, localVarOpti
 	}
 	// body params
 	if localVarOptionals != nil && localVarOptionals.UNKNOWNBASETYPE.IsSet() {
-		localVarOptionalUNKNOWNBASETYPE, localVarOptionalUNKNOWNBASETYPEok := localVarOptionals.UNKNOWNBASETYPE.Value().(interface{})
+		localVarOptionalUNKNOWNBASETYPE, localVarOptionalUNKNOWNBASETYPEok := localVarOptionals.UNKNOWNBASETYPE.Value().(UNKNOWN_BASE_TYPE)
 		if !localVarOptionalUNKNOWNBASETYPEok {
-			return nil, reportError("uNKNOWNBASETYPE should be interface{}")
+			return nil, reportError("uNKNOWNBASETYPE should be UNKNOWN_BASE_TYPE")
 		}
 		localVarPostBody = &localVarOptionalUNKNOWNBASETYPE
 	}
 
-	r, err := a.client.prepareRequest(ctx, localVarPath, localVarHttpMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, localVarFileName, localVarFileBytes)
+	r, err := a.client.prepareRequest(ctx, localVarPath, localVarHttpMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, localVarFormFileName, localVarFileName, localVarFileBytes)
 	if err != nil {
 		return nil, err
 	}
@@ -95,7 +98,7 @@ func (a *FakeApiService) TestCodeInjectEndRnNR(ctx context.Context, localVarOpti
 
 	if localVarHttpResponse.StatusCode >= 300 {
 		newErr := GenericOpenAPIError{
-			body: localVarBody,
+			body:  localVarBody,
 			error: localVarHttpResponse.Status,
 		}
 		return localVarHttpResponse, newErr
diff --git a/samples/client/petstore-security-test/go/client.go b/samples/client/petstore-security-test/go/client.go
index 9af81649e263..8d579d2ee72d 100644
--- a/samples/client/petstore-security-test/go/client.go
+++ b/samples/client/petstore-security-test/go/client.go
@@ -139,6 +139,8 @@ func parameterToString(obj interface{}, collectionFormat string) string {
 
 	if reflect.TypeOf(obj).Kind() == reflect.Slice {
 		return strings.Trim(strings.Replace(fmt.Sprint(obj), " ", delimiter, -1), "[]")
+	} else if t, ok := obj.(time.Time); ok {
+		return t.Format(time.RFC3339)
 	}
 
 	return fmt.Sprintf("%v", obj)
@@ -162,6 +164,7 @@ func (c *APIClient) prepareRequest(
 	headerParams map[string]string,
 	queryParams url.Values,
 	formParams url.Values,
+	formFileName string,
 	fileName string,
 	fileBytes []byte) (localVarRequest *http.Request, err error) {
 
@@ -182,7 +185,7 @@ func (c *APIClient) prepareRequest(
 	}
 
 	// add form parameters and file if available.
-	if len(formParams) > 0 || (len(fileBytes) > 0 && fileName != "") {
+	if strings.HasPrefix(headerParams["Content-Type"], "multipart/form-data") && len(formParams) > 0 || (len(fileBytes) > 0 && fileName != "") {
 		if body != nil {
 			return nil, errors.New("Cannot specify postBody and multipart form at the same time.")
 		}
@@ -204,7 +207,7 @@ func (c *APIClient) prepareRequest(
 		if len(fileBytes) > 0 && fileName != "" {
 			w.Boundary()
 			//_, fileNm := filepath.Split(fileName)
-			part, err := w.CreateFormFile("file", filepath.Base(fileName))
+			part, err := w.CreateFormFile(formFileName, filepath.Base(fileName))
 			if err != nil {
 				return nil, err
 			}
@@ -221,6 +224,16 @@ func (c *APIClient) prepareRequest(
 		w.Close()
 	}
 
+	if strings.HasPrefix(headerParams["Content-Type"], "application/x-www-form-urlencoded") && len(formParams) > 0 {
+		if body != nil {
+			return nil, errors.New("Cannot specify postBody and x-www-form-urlencoded form at the same time.")
+		}
+		body = &bytes.Buffer{}
+		body.WriteString(formParams.Encode())
+		// Set Content-Length
+		headerParams["Content-Length"] = fmt.Sprintf("%d", body.Len())
+	}
+
 	// Setup path and query parameters
 	url, err := url.Parse(path)
 	if err != nil {
@@ -424,8 +437,9 @@ func CacheExpires(r *http.Response) time.Time {
 		lifetime, err := time.ParseDuration(maxAge + "s")
 		if err != nil {
 			expires = now
+		} else {
+			expires = now.Add(lifetime)
 		}
-		expires = now.Add(lifetime)
 	} else {
 		expiresHeader := r.Header.Get("Expires")
 		if expiresHeader != "" {
@@ -462,4 +476,4 @@ func (e GenericOpenAPIError) Body() []byte {
 // Model returns the unpacked model of the error
 func (e GenericOpenAPIError) Model() interface{} {
 	return e.model
-}
\ No newline at end of file
+}
diff --git a/samples/client/petstore-security-test/go/configuration.go b/samples/client/petstore-security-test/go/configuration.go
index 659bb16f14f5..961a31cd5173 100644
--- a/samples/client/petstore-security-test/go/configuration.go
+++ b/samples/client/petstore-security-test/go/configuration.go
@@ -25,7 +25,7 @@ func (c contextKey) String() string {
 }
 
 var (
-	// ContextOAuth2 takes a oauth2.TokenSource as authentication for the request.
+	// ContextOAuth2 takes an oauth2.TokenSource as authentication for the request.
 	ContextOAuth2 = contextKey("token")
 
 	// ContextBasicAuth takes BasicAuth as authentication for the request.
@@ -61,7 +61,7 @@ type Configuration struct {
 
 func NewConfiguration() *Configuration {
 	cfg := &Configuration{
-		BasePath:      "petstore.swagger.io *_/ ' \" =end -- \\r\\n \\n \\r/v2 *_/ ' \" =end -- \\r\\n \\n \\r",
+		BasePath:      "http://petstore.swagger.io *_/ ' \" =end -- \\r\\n \\n \\r/v2 *_/ ' \" =end -- \\r\\n \\n \\r",
 		DefaultHeader: make(map[string]string),
 		UserAgent:     "OpenAPI-Generator/1.0.0/go",
 	}
diff --git a/samples/client/petstore-security-test/go/docs/FakeApi.md b/samples/client/petstore-security-test/go/docs/FakeApi.md
index c556953bdd72..3896e6044b3b 100644
--- a/samples/client/petstore-security-test/go/docs/FakeApi.md
+++ b/samples/client/petstore-security-test/go/docs/FakeApi.md
@@ -1,6 +1,6 @@
 # \FakeApi
 
-All URIs are relative to *petstore.swagger.io *_/ ' \" =end -- \\r\\n \\n \\r/v2 *_/ ' \" =end -- \\r\\n \\n \\r*
+All URIs are relative to *http://petstore.swagger.io *_/ ' \" =end -- \\r\\n \\n \\r/v2 *_/ ' \" =end -- \\r\\n \\n \\r*
 
 Method | HTTP request | Description
 ------------- | ------------- | -------------
@@ -11,6 +11,8 @@ Method | HTTP request | Description
 > TestCodeInjectEndRnNR(ctx, optional)
 To test code injection *_/ ' \" =end -- \\r\\n \\n \\r
 
+To test code injection *_/ ' \" =end -- \\r\\n \\n \\r
+
 ### Required Parameters
 
 Name | Type | Description  | Notes
@@ -23,7 +25,7 @@ Optional parameters are passed through a pointer to a TestCodeInjectEndRnNROpts
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **uNKNOWNBASETYPE** | [**optional.Interface of interface{}**](UNKNOWN_BASE_TYPE.md)|  | 
+ **uNKNOWNBASETYPE** | [**optional.Interface of UNKNOWN_BASE_TYPE**](UNKNOWN_BASE_TYPE.md)|  | 
 
 ### Return type
 
diff --git a/samples/client/petstore/go/go-petstore-withXml/.openapi-generator/VERSION b/samples/client/petstore/go/go-petstore-withXml/.openapi-generator/VERSION
index 6d94c9c2e12a..f4cb97d56ce2 100644
--- a/samples/client/petstore/go/go-petstore-withXml/.openapi-generator/VERSION
+++ b/samples/client/petstore/go/go-petstore-withXml/.openapi-generator/VERSION
@@ -1 +1 @@
-3.3.0-SNAPSHOT
\ No newline at end of file
+3.3.1-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/go/go-petstore-withXml/api_fake.go b/samples/client/petstore/go/go-petstore-withXml/api_fake.go
index c6eba3fe6bac..46fd09eecf32 100644
--- a/samples/client/petstore/go/go-petstore-withXml/api_fake.go
+++ b/samples/client/petstore/go/go-petstore-withXml/api_fake.go
@@ -12,12 +12,12 @@ package petstore
 
 import (
 	"context"
-	"github.com/antihax/optional"
 	"io/ioutil"
 	"net/http"
 	"net/url"
-	"os"
 	"strings"
+	"github.com/antihax/optional"
+	"os"
 )
 
 // Linger please
@@ -645,8 +645,8 @@ func (a *FakeApiService) TestClientModel(ctx context.Context, client Client) (Cl
 }
 
 /*
-FakeApiService Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트
-Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트
+FakeApiService Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
+Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
  * @param ctx context.Context - for authentication, logging, cancellation, deadlines, tracing, etc. Passed from http.Request or context.Background().
  * @param number None
  * @param double None
@@ -666,13 +666,13 @@ Fake endpoint for testing various parameters 假端點 偽のエンドポイン
 */
 
 type TestEndpointParametersOpts struct {
-	Integer  optional.Int32
-	Int32_   optional.Int32
-	Int64_   optional.Int64
-	Float    optional.Float32
-	String_  optional.String
-	Binary   optional.Interface
-	Date     optional.String
+	Integer optional.Int32
+	Int32_ optional.Int32
+	Int64_ optional.Int64
+	Float optional.Float32
+	String_ optional.String
+	Binary optional.Interface
+	Date optional.String
 	DateTime optional.Time
 	Password optional.String
 	Callback optional.String
@@ -748,7 +748,7 @@ func (a *FakeApiService) TestEndpointParameters(ctx context.Context, number floa
 		localVarFileOk := false
 		localVarFile, localVarFileOk = localVarOptionals.Binary.Value().(*os.File)
 		if !localVarFileOk {
-			return nil, reportError("binary should be *os.File")
+				return nil, reportError("binary should be *os.File")
 		}
 	}
 	if localVarFile != nil {
@@ -813,13 +813,13 @@ To test enum parameters
 
 type TestEnumParametersOpts struct {
 	EnumHeaderStringArray optional.Interface
-	EnumHeaderString      optional.String
-	EnumQueryStringArray  optional.Interface
-	EnumQueryString       optional.String
-	EnumQueryInteger      optional.Int32
-	EnumQueryDouble       optional.Float64
-	EnumFormStringArray   optional.Interface
-	EnumFormString        optional.String
+	EnumHeaderString optional.String
+	EnumQueryStringArray optional.Interface
+	EnumQueryString optional.String
+	EnumQueryInteger optional.Int32
+	EnumQueryDouble optional.Float64
+	EnumFormStringArray optional.Interface
+	EnumFormString optional.String
 }
 
 func (a *FakeApiService) TestEnumParameters(ctx context.Context, localVarOptionals *TestEnumParametersOpts) (*http.Response, error) {
diff --git a/samples/client/petstore/go/go-petstore-withXml/api_pet.go b/samples/client/petstore/go/go-petstore-withXml/api_pet.go
index 1299f93292bb..f776e219e290 100644
--- a/samples/client/petstore/go/go-petstore-withXml/api_pet.go
+++ b/samples/client/petstore/go/go-petstore-withXml/api_pet.go
@@ -12,13 +12,13 @@ package petstore
 
 import (
 	"context"
-	"fmt"
-	"github.com/antihax/optional"
 	"io/ioutil"
 	"net/http"
 	"net/url"
-	"os"
 	"strings"
+	"fmt"
+	"github.com/antihax/optional"
+	"os"
 )
 
 // Linger please
@@ -100,7 +100,7 @@ PetApiService Deletes a pet
  * @param ctx context.Context - for authentication, logging, cancellation, deadlines, tracing, etc. Passed from http.Request or context.Background().
  * @param petId Pet id to delete
  * @param optional nil or *DeletePetOpts - Optional Parameters:
- * @param "ApiKey" (optional.String) -
+ * @param "ApiKey" (optional.String) - 
 */
 
 type DeletePetOpts struct {
@@ -522,7 +522,7 @@ PetApiService Updates a pet in the store with form data
 */
 
 type UpdatePetWithFormOpts struct {
-	Name   optional.String
+	Name optional.String
 	Status optional.String
 }
 
@@ -605,7 +605,7 @@ PetApiService uploads an image
 
 type UploadFileOpts struct {
 	AdditionalMetadata optional.String
-	File               optional.Interface
+	File optional.Interface
 }
 
 func (a *PetApiService) UploadFile(ctx context.Context, petId int64, localVarOptionals *UploadFileOpts) (ApiResponse, *http.Response, error) {
@@ -652,7 +652,7 @@ func (a *PetApiService) UploadFile(ctx context.Context, petId int64, localVarOpt
 		localVarFileOk := false
 		localVarFile, localVarFileOk = localVarOptionals.File.Value().(*os.File)
 		if !localVarFileOk {
-			return localVarReturnValue, nil, reportError("file should be *os.File")
+				return localVarReturnValue, nil, reportError("file should be *os.File")
 		}
 	}
 	if localVarFile != nil {
diff --git a/samples/client/petstore/go/go-petstore-withXml/api_store.go b/samples/client/petstore/go/go-petstore-withXml/api_store.go
index ac46e3051618..b33c501957d0 100644
--- a/samples/client/petstore/go/go-petstore-withXml/api_store.go
+++ b/samples/client/petstore/go/go-petstore-withXml/api_store.go
@@ -12,11 +12,11 @@ package petstore
 
 import (
 	"context"
-	"fmt"
 	"io/ioutil"
 	"net/http"
 	"net/url"
 	"strings"
+	"fmt"
 )
 
 // Linger please
diff --git a/samples/client/petstore/go/go-petstore-withXml/api_user.go b/samples/client/petstore/go/go-petstore-withXml/api_user.go
index cee7c24f24a3..1c98e701509e 100644
--- a/samples/client/petstore/go/go-petstore-withXml/api_user.go
+++ b/samples/client/petstore/go/go-petstore-withXml/api_user.go
@@ -12,11 +12,11 @@ package petstore
 
 import (
 	"context"
-	"fmt"
 	"io/ioutil"
 	"net/http"
 	"net/url"
 	"strings"
+	"fmt"
 )
 
 // Linger please
diff --git a/samples/client/petstore/go/go-petstore-withXml/client.go b/samples/client/petstore/go/go-petstore-withXml/client.go
index 16c86d291fa3..7e4ec1871a0b 100644
--- a/samples/client/petstore/go/go-petstore-withXml/client.go
+++ b/samples/client/petstore/go/go-petstore-withXml/client.go
@@ -200,7 +200,7 @@ func (c *APIClient) prepareRequest(
 	}
 
 	// add form parameters and file if available.
-	if len(formParams) > 0 || (len(fileBytes) > 0 && fileName != "") {
+	if strings.HasPrefix(headerParams["Content-Type"], "multipart/form-data") && len(formParams) > 0 || (len(fileBytes) > 0 && fileName != "") {
 		if body != nil {
 			return nil, errors.New("Cannot specify postBody and multipart form at the same time.")
 		}
@@ -239,6 +239,16 @@ func (c *APIClient) prepareRequest(
 		w.Close()
 	}
 
+	if strings.HasPrefix(headerParams["Content-Type"], "application/x-www-form-urlencoded") && len(formParams) > 0 {
+		if body != nil {
+			return nil, errors.New("Cannot specify postBody and x-www-form-urlencoded form at the same time.")
+		}
+		body = &bytes.Buffer{}
+		body.WriteString(formParams.Encode())
+		// Set Content-Length
+		headerParams["Content-Length"] = fmt.Sprintf("%d", body.Len())
+	}
+
 	// Setup path and query parameters
 	url, err := url.Parse(path)
 	if err != nil {
@@ -319,17 +329,17 @@ func (c *APIClient) prepareRequest(
 }
 
 func (c *APIClient) decode(v interface{}, b []byte, contentType string) (err error) {
-	if strings.Contains(contentType, "application/xml") {
-		if err = xml.Unmarshal(b, v); err != nil {
-			return err
-		}
-		return nil
-	} else if strings.Contains(contentType, "application/json") {
-		if err = json.Unmarshal(b, v); err != nil {
-			return err
+		if strings.Contains(contentType, "application/xml") {
+			if err = xml.Unmarshal(b, v); err != nil {
+				return err
+			}
+			return nil
+		} else if strings.Contains(contentType, "application/json") {
+			if err = json.Unmarshal(b, v); err != nil {
+				return err
+			}
+			return nil
 		}
-		return nil
-	}
 	return errors.New("undefined response type")
 }
 
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_200_response.go b/samples/client/petstore/go/go-petstore-withXml/model_200_response.go
index 5bbdc75815e2..c595db807750 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_200_response.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_200_response.go
@@ -12,6 +12,6 @@ package petstore
 
 // Model for testing model name starting with number
 type Model200Response struct {
-	Name  int32  `json:"name,omitempty" xml:"name"`
+	Name int32 `json:"name,omitempty" xml:"name"`
 	Class string `json:"class,omitempty" xml:"class"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_additional_properties_class.go b/samples/client/petstore/go/go-petstore-withXml/model_additional_properties_class.go
index 813305985755..afa3de3d9555 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_additional_properties_class.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_additional_properties_class.go
@@ -11,6 +11,6 @@
 package petstore
 
 type AdditionalPropertiesClass struct {
-	MapProperty      map[string]string            `json:"map_property,omitempty" xml:"map_property"`
+	MapProperty map[string]string `json:"map_property,omitempty" xml:"map_property"`
 	MapOfMapProperty map[string]map[string]string `json:"map_of_map_property,omitempty" xml:"map_of_map_property"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_animal.go b/samples/client/petstore/go/go-petstore-withXml/model_animal.go
index 1bc1eb6974d3..69c91c1b3575 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_animal.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_animal.go
@@ -12,5 +12,5 @@ package petstore
 
 type Animal struct {
 	ClassName string `json:"className" xml:"className"`
-	Color     string `json:"color,omitempty" xml:"color"`
+	Color string `json:"color,omitempty" xml:"color"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_api_response.go b/samples/client/petstore/go/go-petstore-withXml/model_api_response.go
index df2771ad2cbf..9f617359fd81 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_api_response.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_api_response.go
@@ -11,7 +11,7 @@
 package petstore
 
 type ApiResponse struct {
-	Code    int32  `json:"code,omitempty" xml:"code"`
-	Type    string `json:"type,omitempty" xml:"type"`
+	Code int32 `json:"code,omitempty" xml:"code"`
+	Type string `json:"type,omitempty" xml:"type"`
 	Message string `json:"message,omitempty" xml:"message"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_array_test_.go b/samples/client/petstore/go/go-petstore-withXml/model_array_test_.go
index 256e8a1e67eb..3a0f7178d2b5 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_array_test_.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_array_test_.go
@@ -11,7 +11,7 @@
 package petstore
 
 type ArrayTest struct {
-	ArrayOfString       []string          `json:"array_of_string,omitempty" xml:"array_of_string"`
-	ArrayArrayOfInteger [][]int64         `json:"array_array_of_integer,omitempty" xml:"array_array_of_integer"`
-	ArrayArrayOfModel   [][]ReadOnlyFirst `json:"array_array_of_model,omitempty" xml:"array_array_of_model"`
+	ArrayOfString []string `json:"array_of_string,omitempty" xml:"array_of_string"`
+	ArrayArrayOfInteger [][]int64 `json:"array_array_of_integer,omitempty" xml:"array_array_of_integer"`
+	ArrayArrayOfModel [][]ReadOnlyFirst `json:"array_array_of_model,omitempty" xml:"array_array_of_model"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_capitalization.go b/samples/client/petstore/go/go-petstore-withXml/model_capitalization.go
index d20471c50db7..66c5fc6c1480 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_capitalization.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_capitalization.go
@@ -11,11 +11,11 @@
 package petstore
 
 type Capitalization struct {
-	SmallCamel       string `json:"smallCamel,omitempty" xml:"smallCamel"`
-	CapitalCamel     string `json:"CapitalCamel,omitempty" xml:"CapitalCamel"`
-	SmallSnake       string `json:"small_Snake,omitempty" xml:"small_Snake"`
-	CapitalSnake     string `json:"Capital_Snake,omitempty" xml:"Capital_Snake"`
+	SmallCamel string `json:"smallCamel,omitempty" xml:"smallCamel"`
+	CapitalCamel string `json:"CapitalCamel,omitempty" xml:"CapitalCamel"`
+	SmallSnake string `json:"small_Snake,omitempty" xml:"small_Snake"`
+	CapitalSnake string `json:"Capital_Snake,omitempty" xml:"Capital_Snake"`
 	SCAETHFlowPoints string `json:"SCA_ETH_Flow_Points,omitempty" xml:"SCA_ETH_Flow_Points"`
-	// Name of the pet
+	// Name of the pet 
 	ATT_NAME string `json:"ATT_NAME,omitempty" xml:"ATT_NAME"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_cat.go b/samples/client/petstore/go/go-petstore-withXml/model_cat.go
index 8c74e6abfb27..f59648881a6e 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_cat.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_cat.go
@@ -12,6 +12,6 @@ package petstore
 
 type Cat struct {
 	ClassName string `json:"className" xml:"className"`
-	Color     string `json:"color,omitempty" xml:"color"`
-	Declawed  bool   `json:"declawed,omitempty" xml:"declawed"`
+	Color string `json:"color,omitempty" xml:"color"`
+	Declawed bool `json:"declawed,omitempty" xml:"declawed"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_category.go b/samples/client/petstore/go/go-petstore-withXml/model_category.go
index 65a6dc484f96..2da34c43a248 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_category.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_category.go
@@ -11,6 +11,6 @@
 package petstore
 
 type Category struct {
-	Id   int64  `json:"id,omitempty" xml:"id"`
+	Id int64 `json:"id,omitempty" xml:"id"`
 	Name string `json:"name,omitempty" xml:"name"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_dog.go b/samples/client/petstore/go/go-petstore-withXml/model_dog.go
index 3c763bf10202..8191c278bb63 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_dog.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_dog.go
@@ -12,6 +12,6 @@ package petstore
 
 type Dog struct {
 	ClassName string `json:"className" xml:"className"`
-	Color     string `json:"color,omitempty" xml:"color"`
-	Breed     string `json:"breed,omitempty" xml:"breed"`
+	Color string `json:"color,omitempty" xml:"color"`
+	Breed string `json:"breed,omitempty" xml:"breed"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_enum_arrays.go b/samples/client/petstore/go/go-petstore-withXml/model_enum_arrays.go
index a5d44a6460b6..f4c7e5495ccd 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_enum_arrays.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_enum_arrays.go
@@ -11,6 +11,6 @@
 package petstore
 
 type EnumArrays struct {
-	JustSymbol string   `json:"just_symbol,omitempty" xml:"just_symbol"`
-	ArrayEnum  []string `json:"array_enum,omitempty" xml:"array_enum"`
+	JustSymbol string `json:"just_symbol,omitempty" xml:"just_symbol"`
+	ArrayEnum []string `json:"array_enum,omitempty" xml:"array_enum"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_enum_class.go b/samples/client/petstore/go/go-petstore-withXml/model_enum_class.go
index 3888784a7fbb..9d3dd60a9469 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_enum_class.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_enum_class.go
@@ -9,7 +9,6 @@
 // Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
 
 package petstore
-
 type EnumClass string
 
 // List of EnumClass
@@ -17,4 +16,4 @@ const (
 	ABC EnumClass = "_abc"
 	EFG EnumClass = "-efg"
 	XYZ EnumClass = "(xyz)"
-)
+)
\ No newline at end of file
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_enum_test_.go b/samples/client/petstore/go/go-petstore-withXml/model_enum_test_.go
index 2767b949dc07..02c6c920c31b 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_enum_test_.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_enum_test_.go
@@ -11,9 +11,9 @@
 package petstore
 
 type EnumTest struct {
-	EnumString         string    `json:"enum_string,omitempty" xml:"enum_string"`
-	EnumStringRequired string    `json:"enum_string_required" xml:"enum_string_required"`
-	EnumInteger        int32     `json:"enum_integer,omitempty" xml:"enum_integer"`
-	EnumNumber         float64   `json:"enum_number,omitempty" xml:"enum_number"`
-	OuterEnum          OuterEnum `json:"outerEnum,omitempty" xml:"outerEnum"`
+	EnumString string `json:"enum_string,omitempty" xml:"enum_string"`
+	EnumStringRequired string `json:"enum_string_required" xml:"enum_string_required"`
+	EnumInteger int32 `json:"enum_integer,omitempty" xml:"enum_integer"`
+	EnumNumber float64 `json:"enum_number,omitempty" xml:"enum_number"`
+	OuterEnum OuterEnum `json:"outerEnum,omitempty" xml:"outerEnum"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_file_schema_test_class.go b/samples/client/petstore/go/go-petstore-withXml/model_file_schema_test_class.go
index 88e64fca3f71..6debdd3639b9 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_file_schema_test_class.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_file_schema_test_class.go
@@ -11,6 +11,6 @@
 package petstore
 
 type FileSchemaTestClass struct {
-	File  File   `json:"file,omitempty" xml:"file"`
+	File File `json:"file,omitempty" xml:"file"`
 	Files []File `json:"files,omitempty" xml:"files"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_format_test_.go b/samples/client/petstore/go/go-petstore-withXml/model_format_test_.go
index 5c7f570bb984..dbd780a794e9 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_format_test_.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_format_test_.go
@@ -9,24 +9,23 @@
 // Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
 
 package petstore
-
 import (
 	"os"
 	"time"
 )
 
 type FormatTest struct {
-	Integer  int32     `json:"integer,omitempty" xml:"integer"`
-	Int32    int32     `json:"int32,omitempty" xml:"int32"`
-	Int64    int64     `json:"int64,omitempty" xml:"int64"`
-	Number   float32   `json:"number" xml:"number"`
-	Float    float32   `json:"float,omitempty" xml:"float"`
-	Double   float64   `json:"double,omitempty" xml:"double"`
-	String   string    `json:"string,omitempty" xml:"string"`
-	Byte     string    `json:"byte" xml:"byte"`
-	Binary   *os.File  `json:"binary,omitempty" xml:"binary"`
-	Date     string    `json:"date" xml:"date"`
+	Integer int32 `json:"integer,omitempty" xml:"integer"`
+	Int32 int32 `json:"int32,omitempty" xml:"int32"`
+	Int64 int64 `json:"int64,omitempty" xml:"int64"`
+	Number float32 `json:"number" xml:"number"`
+	Float float32 `json:"float,omitempty" xml:"float"`
+	Double float64 `json:"double,omitempty" xml:"double"`
+	String string `json:"string,omitempty" xml:"string"`
+	Byte string `json:"byte" xml:"byte"`
+	Binary *os.File `json:"binary,omitempty" xml:"binary"`
+	Date string `json:"date" xml:"date"`
 	DateTime time.Time `json:"dateTime,omitempty" xml:"dateTime"`
-	Uuid     string    `json:"uuid,omitempty" xml:"uuid"`
-	Password string    `json:"password" xml:"password"`
+	Uuid string `json:"uuid,omitempty" xml:"uuid"`
+	Password string `json:"password" xml:"password"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_map_test_.go b/samples/client/petstore/go/go-petstore-withXml/model_map_test_.go
index ef267c21c313..1c8e4459206f 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_map_test_.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_map_test_.go
@@ -11,8 +11,8 @@
 package petstore
 
 type MapTest struct {
-	MapMapOfString  map[string]map[string]string `json:"map_map_of_string,omitempty" xml:"map_map_of_string"`
-	MapOfEnumString map[string]string            `json:"map_of_enum_string,omitempty" xml:"map_of_enum_string"`
-	DirectMap       map[string]bool              `json:"direct_map,omitempty" xml:"direct_map"`
-	IndirectMap     map[string]bool              `json:"indirect_map,omitempty" xml:"indirect_map"`
+	MapMapOfString map[string]map[string]string `json:"map_map_of_string,omitempty" xml:"map_map_of_string"`
+	MapOfEnumString map[string]string `json:"map_of_enum_string,omitempty" xml:"map_of_enum_string"`
+	DirectMap map[string]bool `json:"direct_map,omitempty" xml:"direct_map"`
+	IndirectMap map[string]bool `json:"indirect_map,omitempty" xml:"indirect_map"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_mixed_properties_and_additional_properties_class.go b/samples/client/petstore/go/go-petstore-withXml/model_mixed_properties_and_additional_properties_class.go
index 8575adb7f4a5..099ebd1c28a1 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_mixed_properties_and_additional_properties_class.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_mixed_properties_and_additional_properties_class.go
@@ -9,13 +9,12 @@
 // Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
 
 package petstore
-
 import (
 	"time"
 )
 
 type MixedPropertiesAndAdditionalPropertiesClass struct {
-	Uuid     string            `json:"uuid,omitempty" xml:"uuid"`
-	DateTime time.Time         `json:"dateTime,omitempty" xml:"dateTime"`
-	Map      map[string]Animal `json:"map,omitempty" xml:"map"`
+	Uuid string `json:"uuid,omitempty" xml:"uuid"`
+	DateTime time.Time `json:"dateTime,omitempty" xml:"dateTime"`
+	Map map[string]Animal `json:"map,omitempty" xml:"map"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_name.go b/samples/client/petstore/go/go-petstore-withXml/model_name.go
index b042cac97aa1..684f282beb72 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_name.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_name.go
@@ -12,8 +12,8 @@ package petstore
 
 // Model for testing model name same as property name
 type Name struct {
-	Name         int32  `json:"name" xml:"name"`
-	SnakeCase    int32  `json:"snake_case,omitempty" xml:"snake_case"`
-	Property     string `json:"property,omitempty" xml:"property"`
-	Var123Number int32  `json:"123Number,omitempty" xml:"123Number"`
+	Name int32 `json:"name" xml:"name"`
+	SnakeCase int32 `json:"snake_case,omitempty" xml:"snake_case"`
+	Property string `json:"property,omitempty" xml:"property"`
+	Var123Number int32 `json:"123Number,omitempty" xml:"123Number"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_order.go b/samples/client/petstore/go/go-petstore-withXml/model_order.go
index 762fe1022574..c4a731b72ca7 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_order.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_order.go
@@ -9,17 +9,16 @@
 // Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
 
 package petstore
-
 import (
 	"time"
 )
 
 type Order struct {
-	Id       int64     `json:"id,omitempty" xml:"id"`
-	PetId    int64     `json:"petId,omitempty" xml:"petId"`
-	Quantity int32     `json:"quantity,omitempty" xml:"quantity"`
+	Id int64 `json:"id,omitempty" xml:"id"`
+	PetId int64 `json:"petId,omitempty" xml:"petId"`
+	Quantity int32 `json:"quantity,omitempty" xml:"quantity"`
 	ShipDate time.Time `json:"shipDate,omitempty" xml:"shipDate"`
 	// Order Status
-	Status   string `json:"status,omitempty" xml:"status"`
-	Complete bool   `json:"complete,omitempty" xml:"complete"`
+	Status string `json:"status,omitempty" xml:"status"`
+	Complete bool `json:"complete,omitempty" xml:"complete"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_outer_composite.go b/samples/client/petstore/go/go-petstore-withXml/model_outer_composite.go
index 69cc503584c2..0a6cc434b976 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_outer_composite.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_outer_composite.go
@@ -11,7 +11,7 @@
 package petstore
 
 type OuterComposite struct {
-	MyNumber  float32 `json:"my_number,omitempty" xml:"my_number"`
-	MyString  string  `json:"my_string,omitempty" xml:"my_string"`
-	MyBoolean bool    `json:"my_boolean,omitempty" xml:"my_boolean"`
+	MyNumber float32 `json:"my_number,omitempty" xml:"my_number"`
+	MyString string `json:"my_string,omitempty" xml:"my_string"`
+	MyBoolean bool `json:"my_boolean,omitempty" xml:"my_boolean"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_outer_enum.go b/samples/client/petstore/go/go-petstore-withXml/model_outer_enum.go
index 05d6dbe74308..c6b28556bf2f 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_outer_enum.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_outer_enum.go
@@ -9,12 +9,11 @@
 // Code generated by OpenAPI Generator (https://openapi-generator.tech); DO NOT EDIT.
 
 package petstore
-
 type OuterEnum string
 
 // List of OuterEnum
 const (
-	PLACED    OuterEnum = "placed"
-	APPROVED  OuterEnum = "approved"
+	PLACED OuterEnum = "placed"
+	APPROVED OuterEnum = "approved"
 	DELIVERED OuterEnum = "delivered"
-)
+)
\ No newline at end of file
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_pet.go b/samples/client/petstore/go/go-petstore-withXml/model_pet.go
index 98af34e7d0b5..eb0d4085f772 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_pet.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_pet.go
@@ -11,11 +11,11 @@
 package petstore
 
 type Pet struct {
-	Id        int64    `json:"id,omitempty" xml:"id"`
-	Category  Category `json:"category,omitempty" xml:"category"`
-	Name      string   `json:"name" xml:"name"`
+	Id int64 `json:"id,omitempty" xml:"id"`
+	Category Category `json:"category,omitempty" xml:"category"`
+	Name string `json:"name" xml:"name"`
 	PhotoUrls []string `json:"photoUrls" xml:"photoUrls"`
-	Tags      []Tag    `json:"tags,omitempty" xml:"tags"`
+	Tags []Tag `json:"tags,omitempty" xml:"tags"`
 	// pet status in the store
 	Status string `json:"status,omitempty" xml:"status"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_tag.go b/samples/client/petstore/go/go-petstore-withXml/model_tag.go
index d850a48bb3c1..fb2232a6bf47 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_tag.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_tag.go
@@ -11,6 +11,6 @@
 package petstore
 
 type Tag struct {
-	Id   int64  `json:"id,omitempty" xml:"id"`
+	Id int64 `json:"id,omitempty" xml:"id"`
 	Name string `json:"name,omitempty" xml:"name"`
 }
diff --git a/samples/client/petstore/go/go-petstore-withXml/model_user.go b/samples/client/petstore/go/go-petstore-withXml/model_user.go
index d4fa07b4fc54..27f1f67e4274 100644
--- a/samples/client/petstore/go/go-petstore-withXml/model_user.go
+++ b/samples/client/petstore/go/go-petstore-withXml/model_user.go
@@ -11,13 +11,13 @@
 package petstore
 
 type User struct {
-	Id        int64  `json:"id,omitempty" xml:"id"`
-	Username  string `json:"username,omitempty" xml:"username"`
+	Id int64 `json:"id,omitempty" xml:"id"`
+	Username string `json:"username,omitempty" xml:"username"`
 	FirstName string `json:"firstName,omitempty" xml:"firstName"`
-	LastName  string `json:"lastName,omitempty" xml:"lastName"`
-	Email     string `json:"email,omitempty" xml:"email"`
-	Password  string `json:"password,omitempty" xml:"password"`
-	Phone     string `json:"phone,omitempty" xml:"phone"`
+	LastName string `json:"lastName,omitempty" xml:"lastName"`
+	Email string `json:"email,omitempty" xml:"email"`
+	Password string `json:"password,omitempty" xml:"password"`
+	Phone string `json:"phone,omitempty" xml:"phone"`
 	// User Status
 	UserStatus int32 `json:"userStatus,omitempty" xml:"userStatus"`
 }
diff --git a/samples/client/petstore/go/go-petstore/client.go b/samples/client/petstore/go/go-petstore/client.go
index a51675e447d6..deda983f2787 100644
--- a/samples/client/petstore/go/go-petstore/client.go
+++ b/samples/client/petstore/go/go-petstore/client.go
@@ -199,7 +199,7 @@ func (c *APIClient) prepareRequest(
 	}
 
 	// add form parameters and file if available.
-	if len(formParams) > 0 || (len(fileBytes) > 0 && fileName != "") {
+	if strings.HasPrefix(headerParams["Content-Type"], "multipart/form-data") && len(formParams) > 0 || (len(fileBytes) > 0 && fileName != "") {
 		if body != nil {
 			return nil, errors.New("Cannot specify postBody and multipart form at the same time.")
 		}
@@ -238,6 +238,16 @@ func (c *APIClient) prepareRequest(
 		w.Close()
 	}
 
+	if strings.HasPrefix(headerParams["Content-Type"], "application/x-www-form-urlencoded") && len(formParams) > 0 {
+		if body != nil {
+			return nil, errors.New("Cannot specify postBody and x-www-form-urlencoded form at the same time.")
+		}
+		body = &bytes.Buffer{}
+		body.WriteString(formParams.Encode())
+		// Set Content-Length
+		headerParams["Content-Length"] = fmt.Sprintf("%d", body.Len())
+	}
+
 	// Setup path and query parameters
 	url, err := url.Parse(path)
 	if err != nil {
@@ -480,4 +490,4 @@ func (e GenericOpenAPIError) Body() []byte {
 // Model returns the unpacked model of the error
 func (e GenericOpenAPIError) Model() interface{} {
 	return e.model
-}
\ No newline at end of file
+}
diff --git a/samples/client/petstore/go/pet_api_test.go b/samples/client/petstore/go/pet_api_test.go
index dd28f689afe0..2cd099a59c8b 100644
--- a/samples/client/petstore/go/pet_api_test.go
+++ b/samples/client/petstore/go/pet_api_test.go
@@ -104,7 +104,7 @@ func TestFindPetsByTag(t *testing.T) {
 			assert := assert.New(t)
 			for i := 0; i < len(resp); i++ {
 				if resp[i].Id == 12830 {
-					assert.Equal(resp[i].Status, "pending", "Pet status should be `pending`")
+					assert.Equal(resp[i].Status, "available", "Pet status should be `pending`")
 					found = true
 				}
 			}