diff --git a/modules/swagger-codegen/src/main/resources/go/api.mustache b/modules/swagger-codegen/src/main/resources/go/api.mustache
index 0b46ce231d6a..1ee2e206581b 100644
--- a/modules/swagger-codegen/src/main/resources/go/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/go/api.mustache
@@ -36,7 +36,7 @@ func New{{classname}}WithBasePath(basePath string) *{{classname}} {
  *
 {{#allParams}}{{#required}} * @param {{paramName}} {{description}}
 {{/required}}{{/allParams}}{{#hasOptionalParams}} * @param optional (nil or map[string]interface{}) with one or more of:
-{{#allParams}}{{^required}} *     @param "{{paramName}}" ({{dataType}}) {{description}}
+{{#allParams}}{{^required}} *	 @param "{{paramName}}" ({{dataType}}) {{description}}
 {{/required}}{{/allParams}}{{/hasOptionalParams}} * @return {{#returnType}}{{^isListContainer}}*{{/isListContainer}}{{{returnType}}}{{/returnType}}
  */
 func (a {{{classname}}}) {{{nickname}}}({{#allParams}}{{#required}}{{paramName}} {{{dataType}}}{{#hasMore}}, {{/hasMore}}{{/required}}{{/allParams}}{{#hasOptionalParams}}localVarOptionals map[string]interface{}{{/hasOptionalParams}}) ({{#returnType}}{{^isListContainer}}*{{/isListContainer}}{{{returnType}}}, {{/returnType}}*APIResponse, error) {
@@ -85,11 +85,24 @@ func (a {{{classname}}}) {{{nickname}}}({{#allParams}}{{#required}}{{paramName}}
 	{{#queryParams}}
 	{{#isListContainer}}
 	var collectionFormat = "{{#collectionFormat}}{{collectionFormat}}{{/collectionFormat}}"
+	{{#required}}
 	localVarQueryParams.Add("{{baseName}}", a.Configuration.APIClient.ParameterToString({{paramName}}, collectionFormat))
-
+	{{/required}}
+	{{^required}}
+	if localVarTempParam, localVarOk := localVarOptionals["{{paramName}}"].({{dataType}}); localVarOptionals != nil && localVarOk {
+		localVarQueryParams.Add("{{baseName}}", a.Configuration.APIClient.ParameterToString(localVarTempParam, collectionFormat))
+	}
+	{{/required}}
 	{{/isListContainer}}
 	{{^isListContainer}}
+	{{#required}}
 	localVarQueryParams.Add("{{baseName}}", a.Configuration.APIClient.ParameterToString({{paramName}}, ""))
+	{{/required}}
+	{{^required}}
+	if localVarTempParam, localVarOk := localVarOptionals["{{paramName}}"].({{dataType}}); localVarOptionals != nil && localVarOk {
+		localVarQueryParams.Add("{{baseName}}", a.Configuration.APIClient.ParameterToString(localVarTempParam, ""))
+	}
+	{{/required}}
 	{{/isListContainer}}
 	{{/queryParams}}
 	{{/hasQueryParams}}
diff --git a/samples/client/petstore/go/go-petstore/fake_api.go b/samples/client/petstore/go/go-petstore/fake_api.go
index 6366bab28994..80e9fc235ca3 100644
--- a/samples/client/petstore/go/go-petstore/fake_api.go
+++ b/samples/client/petstore/go/go-petstore/fake_api.go
@@ -108,16 +108,16 @@ func (a FakeApi) TestClientModel(body Client) (*Client, *APIResponse, error) {
  * @param patternWithoutDelimiter None
  * @param byte_ None
  * @param optional (nil or map[string]interface{}) with one or more of:
- *     @param "integer" (int32) None
- *     @param "int32_" (int32) None
- *     @param "int64_" (int64) None
- *     @param "float" (float32) None
- *     @param "string_" (string) None
- *     @param "binary" (string) None
- *     @param "date" (time.Time) None
- *     @param "dateTime" (time.Time) None
- *     @param "password" (string) None
- *     @param "callback" (string) None
+ *	 @param "integer" (int32) None
+ *	 @param "int32_" (int32) None
+ *	 @param "int64_" (int64) None
+ *	 @param "float" (float32) None
+ *	 @param "string_" (string) None
+ *	 @param "binary" (string) None
+ *	 @param "date" (time.Time) None
+ *	 @param "dateTime" (time.Time) None
+ *	 @param "password" (string) None
+ *	 @param "callback" (string) None
  * @return 
  */
 func (a FakeApi) TestEndpointParameters(number float32, double float64, patternWithoutDelimiter string, byte_ string, localVarOptionals map[string]interface{}) (*APIResponse, error) {
@@ -216,14 +216,14 @@ func (a FakeApi) TestEndpointParameters(number float32, double float64, patternW
  * To test enum parameters
  *
  * @param optional (nil or map[string]interface{}) with one or more of:
- *     @param "enumFormStringArray" ([]string) Form parameter enum test (string array)
- *     @param "enumFormString" (string) Form parameter enum test (string)
- *     @param "enumHeaderStringArray" ([]string) Header parameter enum test (string array)
- *     @param "enumHeaderString" (string) Header parameter enum test (string)
- *     @param "enumQueryStringArray" ([]string) Query parameter enum test (string array)
- *     @param "enumQueryString" (string) Query parameter enum test (string)
- *     @param "enumQueryInteger" (int32) Query parameter enum test (double)
- *     @param "enumQueryDouble" (float64) Query parameter enum test (double)
+ *	 @param "enumFormStringArray" ([]string) Form parameter enum test (string array)
+ *	 @param "enumFormString" (string) Form parameter enum test (string)
+ *	 @param "enumHeaderStringArray" ([]string) Header parameter enum test (string array)
+ *	 @param "enumHeaderString" (string) Header parameter enum test (string)
+ *	 @param "enumQueryStringArray" ([]string) Query parameter enum test (string array)
+ *	 @param "enumQueryString" (string) Query parameter enum test (string)
+ *	 @param "enumQueryInteger" (int32) Query parameter enum test (double)
+ *	 @param "enumQueryDouble" (float64) Query parameter enum test (double)
  * @return 
  */
 func (a FakeApi) TestEnumParameters(localVarOptionals map[string]interface{}) (*APIResponse, error) {
@@ -243,10 +243,15 @@ func (a FakeApi) TestEnumParameters(localVarOptionals map[string]interface{}) (*
 		localVarHeaderParams[key] = a.Configuration.DefaultHeader[key]
 	}
 	var collectionFormat = "csv"
-	localVarQueryParams.Add("enum_query_string_array", a.Configuration.APIClient.ParameterToString(enumQueryStringArray, collectionFormat))
-
-	localVarQueryParams.Add("enum_query_string", a.Configuration.APIClient.ParameterToString(enumQueryString, ""))
-	localVarQueryParams.Add("enum_query_integer", a.Configuration.APIClient.ParameterToString(enumQueryInteger, ""))
+	if localVarTempParam, localVarOk := localVarOptionals["enumQueryStringArray"].([]string); localVarOptionals != nil && localVarOk {
+		localVarQueryParams.Add("enum_query_string_array", a.Configuration.APIClient.ParameterToString(localVarTempParam, collectionFormat))
+	}
+	if localVarTempParam, localVarOk := localVarOptionals["enumQueryString"].(string); localVarOptionals != nil && localVarOk {
+		localVarQueryParams.Add("enum_query_string", a.Configuration.APIClient.ParameterToString(localVarTempParam, ""))
+	}
+	if localVarTempParam, localVarOk := localVarOptionals["enumQueryInteger"].(int32); localVarOptionals != nil && localVarOk {
+		localVarQueryParams.Add("enum_query_integer", a.Configuration.APIClient.ParameterToString(localVarTempParam, ""))
+	}
 
 	// to determine the Content-Type header
 	localVarHttpContentTypes := []string{ "*/*",  }
diff --git a/samples/client/petstore/go/go-petstore/pet_api.go b/samples/client/petstore/go/go-petstore/pet_api.go
index f2c145643771..a7c5d55d635a 100644
--- a/samples/client/petstore/go/go-petstore/pet_api.go
+++ b/samples/client/petstore/go/go-petstore/pet_api.go
@@ -111,7 +111,7 @@ func (a PetApi) AddPet(body Pet) (*APIResponse, error) {
  *
  * @param petId Pet id to delete
  * @param optional (nil or map[string]interface{}) with one or more of:
- *     @param "apiKey" (string) 
+ *	 @param "apiKey" (string) 
  * @return 
  */
 func (a PetApi) DeletePet(petId int64, localVarOptionals map[string]interface{}) (*APIResponse, error) {
@@ -206,7 +206,6 @@ func (a PetApi) FindPetsByStatus(status []string) ([]Pet, *APIResponse, error) {
 	var collectionFormat = "csv"
 	localVarQueryParams.Add("status", a.Configuration.APIClient.ParameterToString(status, collectionFormat))
 
-
 	// to determine the Content-Type header
 	localVarHttpContentTypes := []string{  }
 
@@ -275,7 +274,6 @@ func (a PetApi) FindPetsByTags(tags []string) ([]Pet, *APIResponse, error) {
 	var collectionFormat = "csv"
 	localVarQueryParams.Add("tags", a.Configuration.APIClient.ParameterToString(tags, collectionFormat))
 
-
 	// to determine the Content-Type header
 	localVarHttpContentTypes := []string{  }
 
@@ -450,8 +448,8 @@ func (a PetApi) UpdatePet(body Pet) (*APIResponse, error) {
  *
  * @param petId ID of pet that needs to be updated
  * @param optional (nil or map[string]interface{}) with one or more of:
- *     @param "name" (string) Updated name of the pet
- *     @param "status" (string) Updated status of the pet
+ *	 @param "name" (string) Updated name of the pet
+ *	 @param "status" (string) Updated status of the pet
  * @return 
  */
 func (a PetApi) UpdatePetWithForm(petId int64, localVarOptionals map[string]interface{}) (*APIResponse, error) {
@@ -524,8 +522,8 @@ func (a PetApi) UpdatePetWithForm(petId int64, localVarOptionals map[string]inte
  *
  * @param petId ID of pet to update
  * @param optional (nil or map[string]interface{}) with one or more of:
- *     @param "additionalMetadata" (string) Additional data to pass to server
- *     @param "file" (*os.File) file to upload
+ *	 @param "additionalMetadata" (string) Additional data to pass to server
+ *	 @param "file" (*os.File) file to upload
  * @return *ModelApiResponse
  */
 func (a PetApi) UploadFile(petId int64, localVarOptionals map[string]interface{}) (*ModelApiResponse, *APIResponse, error) {