Issue 11401 - report correctly the parameters with the deep object specification (#13909)

* issue #11401 - Go client generator doesn't support deepObject in query

* samples generation

* fix generation

* fix generation

* generated samples

# Conflicts:
#	samples/client/petstore/go/go-petstore/model_200_response.go
#	samples/client/petstore/go/go-petstore/model_additional_properties_any_type.go
#	samples/client/petstore/go/go-petstore/model_client.go

* Fixed unit tests

* revert to http connection for tests

* fix model_simple generation

* Fix parameter encoding issue

* simplified routine

* fix test url

* adapted for latest master, necessary generation

* samples generation

* sync with new master, regenerate samples

* added api client test

modules/openapi-generator/src/main/resources/go/api.mustache

@@ -124,7 +124,7 @@ func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&class
 	}
 
 	localVarPath := localBasePath + "{{{path}}}"{{#pathParams}}
-	localVarPath = strings.Replace(localVarPath, "{"+"{{baseName}}"+"}", url.PathEscape(parameterToString(r.{{paramName}}, "{{collectionFormat}}")), -1){{/pathParams}}
+	localVarPath = strings.Replace(localVarPath, "{"+"{{baseName}}"+"}", url.PathEscape(parameterValueToString(r.{{paramName}}, "{{paramName}}")), -1){{/pathParams}}
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -189,15 +189,15 @@ func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&class
 		if reflect.TypeOf(t).Kind() == reflect.Slice {
 			s := reflect.ValueOf(t)
 			for i := 0; i < s.Len(); i++ {
-				localVarQueryParams.Add("{{baseName}}", parameterToString(s.Index(i), "{{collectionFormat}}"))
+				parameterAddToQuery(localVarQueryParams, "{{baseName}}", s.Index(i), "{{collectionFormat}}")
 			}
 		} else {
-			localVarQueryParams.Add("{{baseName}}", parameterToString(t, "{{collectionFormat}}"))
+			parameterAddToQuery(localVarQueryParams, "{{baseName}}", t, "{{collectionFormat}}")
 		}
 	}
 	{{/isCollectionFormatMulti}}
 	{{^isCollectionFormatMulti}}
-	localVarQueryParams.Add("{{baseName}}", parameterToString(*r.{{paramName}}, "{{collectionFormat}}"))
+	parameterAddToQuery(localVarQueryParams, "{{baseName}}", r.{{paramName}}, "{{collectionFormat}}")
 	{{/isCollectionFormatMulti}}
 	{{/required}}
 	{{^required}}
@@ -207,14 +207,14 @@ func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&class
 		if reflect.TypeOf(t).Kind() == reflect.Slice {
 			s := reflect.ValueOf(t)
 			for i := 0; i < s.Len(); i++ {
-				localVarQueryParams.Add("{{baseName}}", parameterToString(s.Index(i), "{{collectionFormat}}"))
+				parameterAddToQuery(localVarQueryParams, "{{baseName}}", s.Index(i), "{{collectionFormat}}")
 			}
 		} else {
-			localVarQueryParams.Add("{{baseName}}", parameterToString(t, "{{collectionFormat}}"))
+			parameterAddToQuery(localVarQueryParams, "{{baseName}}", t, "{{collectionFormat}}")
 		}
 	{{/isCollectionFormatMulti}}
 	{{^isCollectionFormatMulti}}
-		localVarQueryParams.Add("{{baseName}}", parameterToString(*r.{{paramName}}, "{{collectionFormat}}"))
+	    parameterAddToQuery(localVarQueryParams, "{{baseName}}", r.{{paramName}}, "{{collectionFormat}}")
 	{{/isCollectionFormatMulti}}
 	}
 	{{/required}}
@@ -242,11 +242,11 @@ func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&class
 	}
 {{#headerParams}}
 	{{#required}}
-	localVarHeaderParams["{{baseName}}"] = parameterToString(*r.{{paramName}}, "{{collectionFormat}}")
+	parameterAddToQuery(localVarQueryParams, "{{baseName}}", r.{{paramName}}, "{{collectionFormat}}")
 	{{/required}}
 	{{^required}}
 	if r.{{paramName}} != nil {
-		localVarHeaderParams["{{baseName}}"] = parameterToString(*r.{{paramName}}, "{{collectionFormat}}")
+		parameterAddToQuery(localVarQueryParams, "{{baseName}}", r.{{paramName}}, "{{collectionFormat}}")
 	}
 	{{/required}}
 {{/headerParams}}
@@ -277,7 +277,7 @@ func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&class
 {{/isFile}}
 {{^isFile}}
 {{#required}}
-	localVarFormParams.Add("{{baseName}}", parameterToString(*r.{{paramName}}, "{{collectionFormat}}"))
+	parameterAddToQuery(localVarFormParams, "{{baseName}}", r.{{paramName}}, "{{collectionFormat}}")
 {{/required}}
 {{^required}}
 {{#isModel}}
@@ -291,7 +291,7 @@ func (a *{{{classname}}}Service) {{nickname}}Execute(r {{#structPrefix}}{{&class
 {{/isModel}}
 {{^isModel}}
 	if r.{{paramName}} != nil {
-		localVarFormParams.Add("{{baseName}}", parameterToString(*r.{{paramName}}, "{{collectionFormat}}"))
+		parameterAddToQuery(localVarFormParams, "{{baseName}}", r.{{paramName}}, "{{collectionFormat}}")
 	}
 {{/isModel}}
 {{/required}}

modules/openapi-generator/src/main/resources/go/client.mustache

@@ -34,6 +34,8 @@ import (
 var (
 	jsonCheck = regexp.MustCompile(`(?i:(?:application|text)/(?:vnd\.[^;]+\+)?json)`)
 	xmlCheck  = regexp.MustCompile(`(?i:(?:application|text)/xml)`)
+    queryParamSplit = regexp.MustCompile(`(^|&)([^&]+)`)
+    queryDescape    = strings.NewReplacer( "%5B", "[", "%5D", "]" )
 )
 
 // APIClient manages communication with the {{appName}} API v{{version}}
@@ -132,29 +134,102 @@ func typeCheckParameter(obj interface{}, expected string, name string) error {
 	return nil
 }
 
-// parameterToString convert interface{} parameters to string, using a delimiter if format is provided.
-func parameterToString(obj interface{}, collectionFormat string) string {
-	var delimiter string
-
-	switch collectionFormat {
-	case "pipes":
-		delimiter = "|"
-	case "ssv":
-		delimiter = " "
-	case "tsv":
-		delimiter = "\t"
-	case "csv":
-		delimiter = ","
-	}
-
-	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)
-	}
-
+func parameterValueToString( obj interface{}, key string ) string {
+    if reflect.TypeOf(obj).Kind() != reflect.Ptr {
         return fmt.Sprintf("%v", obj)
     }
+    var param,ok = obj.(MappedNullable)
+    if !ok {
+        return ""
+    }
+    dataMap,err := param.ToMap()
+    if err != nil {
+        return ""
+    }
+    return fmt.Sprintf("%v", dataMap[key])
+}
+
+// parameterAddToQuery adds the provided object to the url query supporting deep object syntax
+func parameterAddToQuery(queryParams interface{}, keyPrefix string, obj interface{}, collectionType string) {
+    var v = reflect.ValueOf(obj)
+    var value = ""
+    if v == reflect.ValueOf(nil) {
+        value = "null"
+    } else {
+        switch v.Kind() {
+			case reflect.Invalid:
+				value = "invalid"
+
+			case reflect.Struct:
+				if t,ok := obj.(MappedNullable); ok {
+					dataMap,err := t.ToMap()
+					if err != nil {
+						return
+					}
+					parameterAddToQuery(queryParams, keyPrefix, dataMap, collectionType)
+					return
+				}
+				if t, ok := obj.(time.Time); ok {
+					parameterAddToQuery(queryParams, keyPrefix, t.Format(time.RFC3339), collectionType)
+					return
+				}
+				value = v.Type().String() + " value"
+			case reflect.Slice:
+				var indValue = reflect.ValueOf(obj)
+				if indValue == reflect.ValueOf(nil) {
+					return
+				}
+				var lenIndValue = indValue.Len()
+				for i:=0;i<lenIndValue;i++ {
+					var arrayValue = indValue.Index(i)
+					parameterAddToQuery(queryParams, keyPrefix, arrayValue.Interface(), collectionType)
+				}
+				return
+
+			case reflect.Map:
+				var indValue = reflect.ValueOf(obj)
+				if indValue == reflect.ValueOf(nil) {
+					return
+				}
+				iter := indValue.MapRange()
+				for iter.Next() {
+					k,v := iter.Key(), iter.Value()
+					parameterAddToQuery(queryParams, fmt.Sprintf("%s[%s]", keyPrefix, k.String()), v.Interface(), collectionType)
+				}
+				return
+
+			case reflect.Interface:
+				fallthrough
+            case reflect.Ptr:
+				parameterAddToQuery(queryParams, keyPrefix, v.Elem().Interface(), collectionType)
+                return
+
+            case reflect.Int, reflect.Int8, reflect.Int16,
+                reflect.Int32, reflect.Int64:
+                value = strconv.FormatInt(v.Int(), 10)
+            case reflect.Uint, reflect.Uint8, reflect.Uint16,
+                reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+                value = strconv.FormatUint(v.Uint(), 10)
+            case reflect.Float32, reflect.Float64:
+                value = strconv.FormatFloat(v.Float(), 'g', -1, 32)
+            case reflect.Bool:
+                value = strconv.FormatBool(v.Bool())
+            case reflect.String:
+                value = v.String()
+            default:
+                value = v.Type().String() + " value"
+        }
+    }
+
+    switch valuesMap := queryParams.(type) {
+        case url.Values:
+            valuesMap.Add( keyPrefix, value )
+            break
+        case map[string]string:
+            valuesMap[keyPrefix] = value
+            break
+    }
+}
 
 // helper for converting interface{} parameters to json strings
 func parameterToJson(obj interface{}) (string, error) {
@@ -305,7 +380,11 @@ func (c *APIClient) prepareRequest(
 	}
 
 	// Encode the parameters.
-	url.RawQuery = query.Encode()
+    url.RawQuery = queryParamSplit.ReplaceAllStringFunc(query.Encode(), func(s string) string {
+        pieces := strings.Split(s, "=")
+        pieces[0] = queryDescape.Replace(pieces[0])
+        return strings.Join(pieces, "=")
+    })
 
 	// Generate a new request
 	if body != nil {

modules/openapi-generator/src/main/resources/go/model_simple.mustache

@@ -1,3 +1,6 @@
+// checks if the {{classname}} type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &{{classname}}{}
+
 // {{classname}} {{{description}}}{{^description}}struct for {{{classname}}}{{/description}}
 type {{classname}} struct {
 {{#parent}}
@@ -258,17 +261,25 @@ func (o *{{classname}}) Unset{{name}}() {
 {{/required}}
 {{/vars}}
 func (o {{classname}}) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o {{classname}}) ToMap() (map[string]interface{}, error) {
 	toSerialize := {{#isArray}}make([]interface{}, len(o.Items)){{/isArray}}{{^isArray}}map[string]interface{}{}{{/isArray}}
 	{{#parent}}
 	{{^isMap}}
 	{{^isArray}}
 	serialized{{parent}}, err{{parent}} := json.Marshal(o.{{parent}})
 	if err{{parent}} != nil {
-		return []byte{}, err{{parent}}
+		return map[string]interface{}{}, err{{parent}}
 	}
 	err{{parent}} = json.Unmarshal([]byte(serialized{{parent}}), &toSerialize)
 	if err{{parent}} != nil {
-		return []byte{}, err{{parent}}
+		return map[string]interface{}{}, err{{parent}}
 	}
 	{{/isArray}}
 	{{/isMap}}
@@ -288,16 +299,26 @@ func (o {{classname}}) MarshalJSON() ([]byte, error) {
 	}
 	{{/vendorExtensions.x-golang-is-container}}
 	{{^vendorExtensions.x-golang-is-container}}
-	if {{#required}}true{{/required}}{{^required}}o.{{name}}.IsSet(){{/required}} {
+	{{#required}}
+	toSerialize["{{baseName}}"] = o.{{name}}.Get()
+	{{/required}}
+	{{^required}}
+	if o.{{name}}.IsSet() {
 		toSerialize["{{baseName}}"] = o.{{name}}.Get()
 	}
+	{{/required}}
 	{{/vendorExtensions.x-golang-is-container}}
 	{{/isNullable}}
 	{{! if argument is not nullable, don't set it if it is nil}}
 	{{^isNullable}}
-	if {{#required}}true{{/required}}{{^required}}!isNil(o.{{name}}){{/required}} {
+	{{#required}}
+	toSerialize["{{baseName}}"] = o.{{name}}
+	{{/required}}
+	{{^required}}
+	if !isNil(o.{{name}}) {
 		toSerialize["{{baseName}}"] = o.{{name}}
 	}
+	{{/required}}
 	{{/isNullable}}
 	{{/vars}}
 	{{#isAdditionalPropertiesTrue}}
@@ -307,7 +328,7 @@ func (o {{classname}}) MarshalJSON() ([]byte, error) {
 	}
 
 	{{/isAdditionalPropertiesTrue}}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 {{#isAdditionalPropertiesTrue}}

modules/openapi-generator/src/main/resources/go/utils.mustache

@@ -332,3 +332,7 @@ func isNil(i interface{}) bool {
 	}
 	return false
 }
+
+type MappedNullable interface {
+	ToMap() (map[string]interface{}, error)
+}

modules/openapi-generator/src/test/resources/3_0/go/petstore-with-fake-endpoints-models-for-testing-with-http-signature.yaml

@@ -842,7 +842,7 @@ paths:
         '5XX':
           description: Something wrong
           content:
-            'applicatino/json':
+            'application/json':
               schema:
                 $ref: '#/components/schemas/OuterNumber'
   /fake/outer/number:
@@ -1155,6 +1155,29 @@ paths:
             application/json:
               schema:
                 $ref: '#/components/schemas/HealthCheckResult'
+  /fake/deep_object_test:
+    get:
+      tags:
+        - fake
+      operationId: test_query_deep_object
+      parameters:
+        - name: test_pet
+          in: query
+          required: false
+          style: deepObject
+          schema:
+            $ref: '#/components/schemas/Pet'
+          explode: true
+        - name: inputOptions
+          in: query
+          required: false
+          style: deepObject
+          schema:
+            $ref: '#/components/schemas/Category'
+          explode: true
+      responses:
+        '200':
+          description: OK
 servers:
   - url: 'http://{server}.swagger.io:{port}/v2'
     description: petstore server

samples/client/petstore/go/go-petstore/api_fake.go

@@ -902,7 +902,7 @@ func (a *FakeApiService) TestBodyWithQueryParamsExecute(r ApiTestBodyWithQueryPa
 		return nil, reportError("body is required and must be specified")
 	}
 
-	localVarQueryParams.Add("query", parameterToString(*r.query, ""))
+	parameterAddToQuery(localVarQueryParams, "query", r.query, "")
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{"application/json"}
 
@@ -1247,24 +1247,24 @@ func (a *FakeApiService) TestEndpointParametersExecute(r ApiTestEndpointParamete
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.integer != nil {
-		localVarFormParams.Add("integer", parameterToString(*r.integer, ""))
+		parameterAddToQuery(localVarFormParams, "integer", r.integer, "")
 	}
 	if r.int32_ != nil {
-		localVarFormParams.Add("int32", parameterToString(*r.int32_, ""))
+		parameterAddToQuery(localVarFormParams, "int32", r.int32_, "")
 	}
 	if r.int64_ != nil {
-		localVarFormParams.Add("int64", parameterToString(*r.int64_, ""))
+		parameterAddToQuery(localVarFormParams, "int64", r.int64_, "")
 	}
-	localVarFormParams.Add("number", parameterToString(*r.number, ""))
+	parameterAddToQuery(localVarFormParams, "number", r.number, "")
 	if r.float != nil {
-		localVarFormParams.Add("float", parameterToString(*r.float, ""))
+		parameterAddToQuery(localVarFormParams, "float", r.float, "")
 	}
-	localVarFormParams.Add("double", parameterToString(*r.double, ""))
+	parameterAddToQuery(localVarFormParams, "double", r.double, "")
 	if r.string_ != nil {
-		localVarFormParams.Add("string", parameterToString(*r.string_, ""))
+		parameterAddToQuery(localVarFormParams, "string", r.string_, "")
 	}
-	localVarFormParams.Add("pattern_without_delimiter", parameterToString(*r.patternWithoutDelimiter, ""))
-	localVarFormParams.Add("byte", parameterToString(*r.byte_, ""))
+	parameterAddToQuery(localVarFormParams, "pattern_without_delimiter", r.patternWithoutDelimiter, "")
+	parameterAddToQuery(localVarFormParams, "byte", r.byte_, "")
 	var binaryLocalVarFormFileName string
 	var binaryLocalVarFileName     string
 	var binaryLocalVarFileBytes    []byte
@@ -1283,16 +1283,16 @@ func (a *FakeApiService) TestEndpointParametersExecute(r ApiTestEndpointParamete
 	}
 	formFiles = append(formFiles, formFile{fileBytes: binaryLocalVarFileBytes, fileName: binaryLocalVarFileName, formFileName: binaryLocalVarFormFileName})
 	if r.date != nil {
-		localVarFormParams.Add("date", parameterToString(*r.date, ""))
+		parameterAddToQuery(localVarFormParams, "date", r.date, "")
 	}
 	if r.dateTime != nil {
-		localVarFormParams.Add("dateTime", parameterToString(*r.dateTime, ""))
+		parameterAddToQuery(localVarFormParams, "dateTime", r.dateTime, "")
 	}
 	if r.password != nil {
-		localVarFormParams.Add("password", parameterToString(*r.password, ""))
+		parameterAddToQuery(localVarFormParams, "password", r.password, "")
 	}
 	if r.callback != nil {
-		localVarFormParams.Add("callback", parameterToString(*r.callback, ""))
+		parameterAddToQuery(localVarFormParams, "callback", r.callback, "")
 	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
@@ -1422,16 +1422,16 @@ func (a *FakeApiService) TestEnumParametersExecute(r ApiTestEnumParametersReques
 	localVarFormParams := url.Values{}
 
 	if r.enumQueryStringArray != nil {
-		localVarQueryParams.Add("enum_query_string_array", parameterToString(*r.enumQueryStringArray, "csv"))
+	    parameterAddToQuery(localVarQueryParams, "enum_query_string_array", r.enumQueryStringArray, "csv")
 	}
 	if r.enumQueryString != nil {
-		localVarQueryParams.Add("enum_query_string", parameterToString(*r.enumQueryString, ""))
+	    parameterAddToQuery(localVarQueryParams, "enum_query_string", r.enumQueryString, "")
 	}
 	if r.enumQueryInteger != nil {
-		localVarQueryParams.Add("enum_query_integer", parameterToString(*r.enumQueryInteger, ""))
+	    parameterAddToQuery(localVarQueryParams, "enum_query_integer", r.enumQueryInteger, "")
 	}
 	if r.enumQueryDouble != nil {
-		localVarQueryParams.Add("enum_query_double", parameterToString(*r.enumQueryDouble, ""))
+	    parameterAddToQuery(localVarQueryParams, "enum_query_double", r.enumQueryDouble, "")
 	}
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{"application/x-www-form-urlencoded"}
@@ -1451,16 +1451,16 @@ func (a *FakeApiService) TestEnumParametersExecute(r ApiTestEnumParametersReques
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.enumHeaderStringArray != nil {
-		localVarHeaderParams["enum_header_string_array"] = parameterToString(*r.enumHeaderStringArray, "csv")
+		parameterAddToQuery(localVarQueryParams, "enum_header_string_array", r.enumHeaderStringArray, "csv")
 	}
 	if r.enumHeaderString != nil {
-		localVarHeaderParams["enum_header_string"] = parameterToString(*r.enumHeaderString, "")
+		parameterAddToQuery(localVarQueryParams, "enum_header_string", r.enumHeaderString, "")
 	}
 	if r.enumFormStringArray != nil {
-		localVarFormParams.Add("enum_form_string_array", parameterToString(*r.enumFormStringArray, "csv"))
+		parameterAddToQuery(localVarFormParams, "enum_form_string_array", r.enumFormStringArray, "csv")
 	}
 	if r.enumFormString != nil {
-		localVarFormParams.Add("enum_form_string", parameterToString(*r.enumFormString, ""))
+		parameterAddToQuery(localVarFormParams, "enum_form_string", r.enumFormString, "")
 	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
@@ -1584,13 +1584,13 @@ func (a *FakeApiService) TestGroupParametersExecute(r ApiTestGroupParametersRequ
 		return nil, reportError("requiredInt64Group is required and must be specified")
 	}
 
-	localVarQueryParams.Add("required_string_group", parameterToString(*r.requiredStringGroup, ""))
-	localVarQueryParams.Add("required_int64_group", parameterToString(*r.requiredInt64Group, ""))
+	parameterAddToQuery(localVarQueryParams, "required_string_group", r.requiredStringGroup, "")
+	parameterAddToQuery(localVarQueryParams, "required_int64_group", r.requiredInt64Group, "")
 	if r.stringGroup != nil {
-		localVarQueryParams.Add("string_group", parameterToString(*r.stringGroup, ""))
+	    parameterAddToQuery(localVarQueryParams, "string_group", r.stringGroup, "")
 	}
 	if r.int64Group != nil {
-		localVarQueryParams.Add("int64_group", parameterToString(*r.int64Group, ""))
+	    parameterAddToQuery(localVarQueryParams, "int64_group", r.int64Group, "")
 	}
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{}
@@ -1609,9 +1609,9 @@ func (a *FakeApiService) TestGroupParametersExecute(r ApiTestGroupParametersRequ
 	if localVarHTTPHeaderAccept != "" {
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
-	localVarHeaderParams["required_boolean_group"] = parameterToString(*r.requiredBooleanGroup, "")
+	parameterAddToQuery(localVarQueryParams, "required_boolean_group", r.requiredBooleanGroup, "")
 	if r.booleanGroup != nil {
-		localVarHeaderParams["boolean_group"] = parameterToString(*r.booleanGroup, "")
+		parameterAddToQuery(localVarQueryParams, "boolean_group", r.booleanGroup, "")
 	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
@@ -1817,8 +1817,8 @@ func (a *FakeApiService) TestJsonFormDataExecute(r ApiTestJsonFormDataRequest) (
 	if localVarHTTPHeaderAccept != "" {
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
-	localVarFormParams.Add("param", parameterToString(*r.param, ""))
-	localVarFormParams.Add("param2", parameterToString(*r.param2, ""))
+	parameterAddToQuery(localVarFormParams, "param", r.param, "")
+	parameterAddToQuery(localVarFormParams, "param2", r.param2, "")
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
 		return nil, err
@@ -1935,19 +1935,19 @@ func (a *FakeApiService) TestQueryParameterCollectionFormatExecute(r ApiTestQuer
 		return nil, reportError("context is required and must be specified")
 	}
 
-	localVarQueryParams.Add("pipe", parameterToString(*r.pipe, "csv"))
-	localVarQueryParams.Add("ioutil", parameterToString(*r.ioutil, "csv"))
-	localVarQueryParams.Add("http", parameterToString(*r.http, "ssv"))
-	localVarQueryParams.Add("url", parameterToString(*r.url, "csv"))
+	parameterAddToQuery(localVarQueryParams, "pipe", r.pipe, "csv")
+	parameterAddToQuery(localVarQueryParams, "ioutil", r.ioutil, "csv")
+	parameterAddToQuery(localVarQueryParams, "http", r.http, "ssv")
+	parameterAddToQuery(localVarQueryParams, "url", r.url, "csv")
 	{
 		t := *r.context
 		if reflect.TypeOf(t).Kind() == reflect.Slice {
 			s := reflect.ValueOf(t)
 			for i := 0; i < s.Len(); i++ {
-				localVarQueryParams.Add("context", parameterToString(s.Index(i), "multi"))
+				parameterAddToQuery(localVarQueryParams, "context", s.Index(i), "multi")
 			}
 		} else {
-			localVarQueryParams.Add("context", parameterToString(t, "multi"))
+			parameterAddToQuery(localVarQueryParams, "context", t, "multi")
 		}
 	}
 	// to determine the Content-Type header

samples/client/petstore/go/go-petstore/api_pet.go

@@ -288,7 +288,7 @@ func (a *PetApiService) DeletePetExecute(r ApiDeletePetRequest) (*http.Response,
 	}
 
 	localVarPath := localBasePath + "/pet/{petId}"
-	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterToString(r.petId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterValueToString(r.petId, "petId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -312,7 +312,7 @@ func (a *PetApiService) DeletePetExecute(r ApiDeletePetRequest) (*http.Response,
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.apiKey != nil {
-		localVarHeaderParams["api_key"] = parameterToString(*r.apiKey, "")
+		parameterAddToQuery(localVarQueryParams, "api_key", r.apiKey, "")
 	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
@@ -397,7 +397,7 @@ func (a *PetApiService) FindPetsByStatusExecute(r ApiFindPetsByStatusRequest) ([
 		return localVarReturnValue, nil, reportError("status is required and must be specified")
 	}
 
-	localVarQueryParams.Add("status", parameterToString(*r.status, "csv"))
+	parameterAddToQuery(localVarQueryParams, "status", r.status, "csv")
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{}
 
@@ -510,7 +510,7 @@ func (a *PetApiService) FindPetsByTagsExecute(r ApiFindPetsByTagsRequest) ([]Pet
 		return localVarReturnValue, nil, reportError("tags is required and must be specified")
 	}
 
-	localVarQueryParams.Add("tags", parameterToString(*r.tags, "csv"))
+	parameterAddToQuery(localVarQueryParams, "tags", r.tags, "csv")
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{}
 
@@ -608,7 +608,7 @@ func (a *PetApiService) GetPetByIdExecute(r ApiGetPetByIdRequest) (*Pet, *http.R
 	}
 
 	localVarPath := localBasePath + "/pet/{petId}"
-	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterToString(r.petId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterValueToString(r.petId, "petId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -833,7 +833,7 @@ func (a *PetApiService) UpdatePetWithFormExecute(r ApiUpdatePetWithFormRequest)
 	}
 
 	localVarPath := localBasePath + "/pet/{petId}"
-	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterToString(r.petId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterValueToString(r.petId, "petId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -857,10 +857,10 @@ func (a *PetApiService) UpdatePetWithFormExecute(r ApiUpdatePetWithFormRequest)
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.name != nil {
-		localVarFormParams.Add("name", parameterToString(*r.name, ""))
+		parameterAddToQuery(localVarFormParams, "name", r.name, "")
 	}
 	if r.status != nil {
-		localVarFormParams.Add("status", parameterToString(*r.status, ""))
+		parameterAddToQuery(localVarFormParams, "status", r.status, "")
 	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
@@ -945,7 +945,7 @@ func (a *PetApiService) UploadFileExecute(r ApiUploadFileRequest) (*ApiResponse,
 	}
 
 	localVarPath := localBasePath + "/pet/{petId}/uploadImage"
-	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterToString(r.petId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterValueToString(r.petId, "petId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -969,7 +969,7 @@ func (a *PetApiService) UploadFileExecute(r ApiUploadFileRequest) (*ApiResponse,
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.additionalMetadata != nil {
-		localVarFormParams.Add("additionalMetadata", parameterToString(*r.additionalMetadata, ""))
+		parameterAddToQuery(localVarFormParams, "additionalMetadata", r.additionalMetadata, "")
 	}
 	var fileLocalVarFormFileName string
 	var fileLocalVarFileName     string
@@ -1080,7 +1080,7 @@ func (a *PetApiService) UploadFileWithRequiredFileExecute(r ApiUploadFileWithReq
 	}
 
 	localVarPath := localBasePath + "/fake/{petId}/uploadImageWithRequiredFile"
-	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterToString(r.petId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterValueToString(r.petId, "petId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -1107,7 +1107,7 @@ func (a *PetApiService) UploadFileWithRequiredFileExecute(r ApiUploadFileWithReq
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.additionalMetadata != nil {
-		localVarFormParams.Add("additionalMetadata", parameterToString(*r.additionalMetadata, ""))
+		parameterAddToQuery(localVarFormParams, "additionalMetadata", r.additionalMetadata, "")
 	}
 	var requiredFileLocalVarFormFileName string
 	var requiredFileLocalVarFileName     string

samples/client/petstore/go/go-petstore/api_store.go

@@ -122,7 +122,7 @@ func (a *StoreApiService) DeleteOrderExecute(r ApiDeleteOrderRequest) (*http.Res
 	}
 
 	localVarPath := localBasePath + "/store/order/{order_id}"
-	localVarPath = strings.Replace(localVarPath, "{"+"order_id"+"}", url.PathEscape(parameterToString(r.orderId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"order_id"+"}", url.PathEscape(parameterValueToString(r.orderId, "orderId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -329,7 +329,7 @@ func (a *StoreApiService) GetOrderByIdExecute(r ApiGetOrderByIdRequest) (*Order,
 	}
 
 	localVarPath := localBasePath + "/store/order/{order_id}"
-	localVarPath = strings.Replace(localVarPath, "{"+"order_id"+"}", url.PathEscape(parameterToString(r.orderId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"order_id"+"}", url.PathEscape(parameterValueToString(r.orderId, "orderId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}

samples/client/petstore/go/go-petstore/api_user.go

@@ -462,7 +462,7 @@ func (a *UserApiService) DeleteUserExecute(r ApiDeleteUserRequest) (*http.Respon
 	}
 
 	localVarPath := localBasePath + "/user/{username}"
-	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterToString(r.username, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterValueToString(r.username, "username")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -554,7 +554,7 @@ func (a *UserApiService) GetUserByNameExecute(r ApiGetUserByNameRequest) (*User,
 	}
 
 	localVarPath := localBasePath + "/user/{username}"
-	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterToString(r.username, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterValueToString(r.username, "username")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -677,8 +677,8 @@ func (a *UserApiService) LoginUserExecute(r ApiLoginUserRequest) (string, *http.
 		return localVarReturnValue, nil, reportError("password is required and must be specified")
 	}
 
-	localVarQueryParams.Add("username", parameterToString(*r.username, ""))
-	localVarQueryParams.Add("password", parameterToString(*r.password, ""))
+	parameterAddToQuery(localVarQueryParams, "username", r.username, "")
+	parameterAddToQuery(localVarQueryParams, "password", r.password, "")
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{}
 
@@ -867,7 +867,7 @@ func (a *UserApiService) UpdateUserExecute(r ApiUpdateUserRequest) (*http.Respon
 	}
 
 	localVarPath := localBasePath + "/user/{username}"
-	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterToString(r.username, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterValueToString(r.username, "username")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}

samples/client/petstore/go/go-petstore/client.go

@@ -39,6 +39,8 @@ import (
 var (
 	jsonCheck = regexp.MustCompile(`(?i:(?:application|text)/(?:vnd\.[^;]+\+)?json)`)
 	xmlCheck  = regexp.MustCompile(`(?i:(?:application|text)/xml)`)
+    queryParamSplit = regexp.MustCompile(`(^|&)([^&]+)`)
+    queryDescape    = strings.NewReplacer( "%5B", "[", "%5D", "]" )
 )
 
 // APIClient manages communication with the OpenAPI Petstore API v1.0.0
@@ -140,29 +142,102 @@ func typeCheckParameter(obj interface{}, expected string, name string) error {
 	return nil
 }
 
-// parameterToString convert interface{} parameters to string, using a delimiter if format is provided.
-func parameterToString(obj interface{}, collectionFormat string) string {
-	var delimiter string
-
-	switch collectionFormat {
-	case "pipes":
-		delimiter = "|"
-	case "ssv":
-		delimiter = " "
-	case "tsv":
-		delimiter = "\t"
-	case "csv":
-		delimiter = ","
-	}
-
-	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)
-	}
-
+func parameterValueToString( obj interface{}, key string ) string {
+    if reflect.TypeOf(obj).Kind() != reflect.Ptr {
         return fmt.Sprintf("%v", obj)
     }
+    var param,ok = obj.(MappedNullable)
+    if !ok {
+        return ""
+    }
+    dataMap,err := param.ToMap()
+    if err != nil {
+        return ""
+    }
+    return fmt.Sprintf("%v", dataMap[key])
+}
+
+// parameterAddToQuery adds the provided object to the url query supporting deep object syntax
+func parameterAddToQuery(queryParams interface{}, keyPrefix string, obj interface{}, collectionType string) {
+    var v = reflect.ValueOf(obj)
+    var value = ""
+    if v == reflect.ValueOf(nil) {
+        value = "null"
+    } else {
+        switch v.Kind() {
+			case reflect.Invalid:
+				value = "invalid"
+
+			case reflect.Struct:
+				if t,ok := obj.(MappedNullable); ok {
+					dataMap,err := t.ToMap()
+					if err != nil {
+						return
+					}
+					parameterAddToQuery(queryParams, keyPrefix, dataMap, collectionType)
+					return
+				}
+				if t, ok := obj.(time.Time); ok {
+					parameterAddToQuery(queryParams, keyPrefix, t.Format(time.RFC3339), collectionType)
+					return
+				}
+				value = v.Type().String() + " value"
+			case reflect.Slice:
+				var indValue = reflect.ValueOf(obj)
+				if indValue == reflect.ValueOf(nil) {
+					return
+				}
+				var lenIndValue = indValue.Len()
+				for i:=0;i<lenIndValue;i++ {
+					var arrayValue = indValue.Index(i)
+					parameterAddToQuery(queryParams, keyPrefix, arrayValue.Interface(), collectionType)
+				}
+				return
+
+			case reflect.Map:
+				var indValue = reflect.ValueOf(obj)
+				if indValue == reflect.ValueOf(nil) {
+					return
+				}
+				iter := indValue.MapRange()
+				for iter.Next() {
+					k,v := iter.Key(), iter.Value()
+					parameterAddToQuery(queryParams, fmt.Sprintf("%s[%s]", keyPrefix, k.String()), v.Interface(), collectionType)
+				}
+				return
+
+			case reflect.Interface:
+				fallthrough
+            case reflect.Ptr:
+				parameterAddToQuery(queryParams, keyPrefix, v.Elem().Interface(), collectionType)
+                return
+
+            case reflect.Int, reflect.Int8, reflect.Int16,
+                reflect.Int32, reflect.Int64:
+                value = strconv.FormatInt(v.Int(), 10)
+            case reflect.Uint, reflect.Uint8, reflect.Uint16,
+                reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+                value = strconv.FormatUint(v.Uint(), 10)
+            case reflect.Float32, reflect.Float64:
+                value = strconv.FormatFloat(v.Float(), 'g', -1, 32)
+            case reflect.Bool:
+                value = strconv.FormatBool(v.Bool())
+            case reflect.String:
+                value = v.String()
+            default:
+                value = v.Type().String() + " value"
+        }
+    }
+
+    switch valuesMap := queryParams.(type) {
+        case url.Values:
+            valuesMap.Add( keyPrefix, value )
+            break
+        case map[string]string:
+            valuesMap[keyPrefix] = value
+            break
+    }
+}
 
 // helper for converting interface{} parameters to json strings
 func parameterToJson(obj interface{}) (string, error) {
@@ -313,7 +388,11 @@ func (c *APIClient) prepareRequest(
 	}
 
 	// Encode the parameters.
-	url.RawQuery = query.Encode()
+    url.RawQuery = queryParamSplit.ReplaceAllStringFunc(query.Encode(), func(s string) string {
+        pieces := strings.Split(s, "=")
+        pieces[0] = queryDescape.Replace(pieces[0])
+        return strings.Join(pieces, "=")
+    })
 
 	// Generate a new request
 	if body != nil {

samples/client/petstore/go/go-petstore/model_200_response.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Model200Response type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Model200Response{}
+
 // Model200Response Model for testing model name starting with number
 type Model200Response struct {
 	Name *int32 `json:"name,omitempty"`
@@ -102,6 +105,14 @@ func (o *Model200Response) SetClass(v string) {
 }
 
 func (o Model200Response) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Model200Response) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Name) {
 		toSerialize["name"] = o.Name
@@ -109,7 +120,7 @@ func (o Model200Response) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Class) {
 		toSerialize["class"] = o.Class
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableModel200Response struct {

samples/client/petstore/go/go-petstore/model_additional_properties_any_type.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the AdditionalPropertiesAnyType type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &AdditionalPropertiesAnyType{}
+
 // AdditionalPropertiesAnyType struct for AdditionalPropertiesAnyType
 type AdditionalPropertiesAnyType struct {
 	Name *string `json:"name,omitempty"`
@@ -69,11 +72,19 @@ func (o *AdditionalPropertiesAnyType) SetName(v string) {
 }
 
 func (o AdditionalPropertiesAnyType) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o AdditionalPropertiesAnyType) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Name) {
 		toSerialize["name"] = o.Name
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableAdditionalPropertiesAnyType struct {

samples/client/petstore/go/go-petstore/model_additional_properties_array.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the AdditionalPropertiesArray type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &AdditionalPropertiesArray{}
+
 // AdditionalPropertiesArray struct for AdditionalPropertiesArray
 type AdditionalPropertiesArray struct {
 	Name *string `json:"name,omitempty"`
@@ -69,11 +72,19 @@ func (o *AdditionalPropertiesArray) SetName(v string) {
 }
 
 func (o AdditionalPropertiesArray) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o AdditionalPropertiesArray) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Name) {
 		toSerialize["name"] = o.Name
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableAdditionalPropertiesArray struct {

samples/client/petstore/go/go-petstore/model_additional_properties_boolean.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the AdditionalPropertiesBoolean type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &AdditionalPropertiesBoolean{}
+
 // AdditionalPropertiesBoolean struct for AdditionalPropertiesBoolean
 type AdditionalPropertiesBoolean struct {
 	Name *string `json:"name,omitempty"`
@@ -69,11 +72,19 @@ func (o *AdditionalPropertiesBoolean) SetName(v string) {
 }
 
 func (o AdditionalPropertiesBoolean) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o AdditionalPropertiesBoolean) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Name) {
 		toSerialize["name"] = o.Name
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableAdditionalPropertiesBoolean struct {

samples/client/petstore/go/go-petstore/model_additional_properties_class.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the AdditionalPropertiesClass type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &AdditionalPropertiesClass{}
+
 // AdditionalPropertiesClass struct for AdditionalPropertiesClass
 type AdditionalPropertiesClass struct {
 	MapString *map[string]string `json:"map_string,omitempty"`
@@ -399,6 +402,14 @@ func (o *AdditionalPropertiesClass) SetAnytype3(v map[string]interface{}) {
 }
 
 func (o AdditionalPropertiesClass) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o AdditionalPropertiesClass) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.MapString) {
 		toSerialize["map_string"] = o.MapString
@@ -433,7 +444,7 @@ func (o AdditionalPropertiesClass) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Anytype3) {
 		toSerialize["anytype_3"] = o.Anytype3
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableAdditionalPropertiesClass struct {

samples/client/petstore/go/go-petstore/model_additional_properties_integer.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the AdditionalPropertiesInteger type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &AdditionalPropertiesInteger{}
+
 // AdditionalPropertiesInteger struct for AdditionalPropertiesInteger
 type AdditionalPropertiesInteger struct {
 	Name *string `json:"name,omitempty"`
@@ -69,11 +72,19 @@ func (o *AdditionalPropertiesInteger) SetName(v string) {
 }
 
 func (o AdditionalPropertiesInteger) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o AdditionalPropertiesInteger) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Name) {
 		toSerialize["name"] = o.Name
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableAdditionalPropertiesInteger struct {

samples/client/petstore/go/go-petstore/model_additional_properties_number.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the AdditionalPropertiesNumber type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &AdditionalPropertiesNumber{}
+
 // AdditionalPropertiesNumber struct for AdditionalPropertiesNumber
 type AdditionalPropertiesNumber struct {
 	Name *string `json:"name,omitempty"`
@@ -69,11 +72,19 @@ func (o *AdditionalPropertiesNumber) SetName(v string) {
 }
 
 func (o AdditionalPropertiesNumber) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o AdditionalPropertiesNumber) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Name) {
 		toSerialize["name"] = o.Name
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableAdditionalPropertiesNumber struct {

samples/client/petstore/go/go-petstore/model_additional_properties_object.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the AdditionalPropertiesObject type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &AdditionalPropertiesObject{}
+
 // AdditionalPropertiesObject struct for AdditionalPropertiesObject
 type AdditionalPropertiesObject struct {
 	Name *string `json:"name,omitempty"`
@@ -69,11 +72,19 @@ func (o *AdditionalPropertiesObject) SetName(v string) {
 }
 
 func (o AdditionalPropertiesObject) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o AdditionalPropertiesObject) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Name) {
 		toSerialize["name"] = o.Name
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableAdditionalPropertiesObject struct {

samples/client/petstore/go/go-petstore/model_additional_properties_string.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the AdditionalPropertiesString type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &AdditionalPropertiesString{}
+
 // AdditionalPropertiesString struct for AdditionalPropertiesString
 type AdditionalPropertiesString struct {
 	Name *string `json:"name,omitempty"`
@@ -69,11 +72,19 @@ func (o *AdditionalPropertiesString) SetName(v string) {
 }
 
 func (o AdditionalPropertiesString) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o AdditionalPropertiesString) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Name) {
 		toSerialize["name"] = o.Name
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableAdditionalPropertiesString struct {

samples/client/petstore/go/go-petstore/model_animal.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Animal type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Animal{}
+
 // Animal struct for Animal
 type Animal struct {
 	ClassName string `json:"className"`
@@ -99,14 +102,20 @@ func (o *Animal) SetColor(v string) {
 }
 
 func (o Animal) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if true {
-		toSerialize["className"] = o.ClassName
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
 	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Animal) ToMap() (map[string]interface{}, error) {
+	toSerialize := map[string]interface{}{}
+	toSerialize["className"] = o.ClassName
 	if !isNil(o.Color) {
 		toSerialize["color"] = o.Color
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableAnimal struct {

samples/client/petstore/go/go-petstore/model_api_response.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ApiResponse type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ApiResponse{}
+
 // ApiResponse struct for ApiResponse
 type ApiResponse struct {
 	Code *int32 `json:"code,omitempty"`
@@ -135,6 +138,14 @@ func (o *ApiResponse) SetMessage(v string) {
 }
 
 func (o ApiResponse) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ApiResponse) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Code) {
 		toSerialize["code"] = o.Code
@@ -145,7 +156,7 @@ func (o ApiResponse) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Message) {
 		toSerialize["message"] = o.Message
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableApiResponse struct {

samples/client/petstore/go/go-petstore/model_array_of_array_of_number_only.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ArrayOfArrayOfNumberOnly type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ArrayOfArrayOfNumberOnly{}
+
 // ArrayOfArrayOfNumberOnly struct for ArrayOfArrayOfNumberOnly
 type ArrayOfArrayOfNumberOnly struct {
 	ArrayArrayNumber [][]float32 `json:"ArrayArrayNumber,omitempty"`
@@ -69,11 +72,19 @@ func (o *ArrayOfArrayOfNumberOnly) SetArrayArrayNumber(v [][]float32) {
 }
 
 func (o ArrayOfArrayOfNumberOnly) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ArrayOfArrayOfNumberOnly) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.ArrayArrayNumber) {
 		toSerialize["ArrayArrayNumber"] = o.ArrayArrayNumber
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableArrayOfArrayOfNumberOnly struct {

samples/client/petstore/go/go-petstore/model_array_of_number_only.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ArrayOfNumberOnly type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ArrayOfNumberOnly{}
+
 // ArrayOfNumberOnly struct for ArrayOfNumberOnly
 type ArrayOfNumberOnly struct {
 	ArrayNumber []float32 `json:"ArrayNumber,omitempty"`
@@ -69,11 +72,19 @@ func (o *ArrayOfNumberOnly) SetArrayNumber(v []float32) {
 }
 
 func (o ArrayOfNumberOnly) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ArrayOfNumberOnly) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.ArrayNumber) {
 		toSerialize["ArrayNumber"] = o.ArrayNumber
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableArrayOfNumberOnly struct {

samples/client/petstore/go/go-petstore/model_array_test_.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ArrayTest type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ArrayTest{}
+
 // ArrayTest struct for ArrayTest
 type ArrayTest struct {
 	ArrayOfString []string `json:"array_of_string,omitempty"`
@@ -135,6 +138,14 @@ func (o *ArrayTest) SetArrayArrayOfModel(v [][]ReadOnlyFirst) {
 }
 
 func (o ArrayTest) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ArrayTest) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.ArrayOfString) {
 		toSerialize["array_of_string"] = o.ArrayOfString
@@ -145,7 +156,7 @@ func (o ArrayTest) MarshalJSON() ([]byte, error) {
 	if !isNil(o.ArrayArrayOfModel) {
 		toSerialize["array_array_of_model"] = o.ArrayArrayOfModel
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableArrayTest struct {

samples/client/petstore/go/go-petstore/model_big_cat.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the BigCat type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &BigCat{}
+
 // BigCat struct for BigCat
 type BigCat struct {
 	Cat
@@ -73,19 +76,27 @@ func (o *BigCat) SetKind(v string) {
 }
 
 func (o BigCat) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o BigCat) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	serializedCat, errCat := json.Marshal(o.Cat)
 	if errCat != nil {
-		return []byte{}, errCat
+		return map[string]interface{}{}, errCat
 	}
 	errCat = json.Unmarshal([]byte(serializedCat), &toSerialize)
 	if errCat != nil {
-		return []byte{}, errCat
+		return map[string]interface{}{}, errCat
 	}
 	if !isNil(o.Kind) {
 		toSerialize["kind"] = o.Kind
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableBigCat struct {

samples/client/petstore/go/go-petstore/model_big_cat_all_of.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the BigCatAllOf type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &BigCatAllOf{}
+
 // BigCatAllOf struct for BigCatAllOf
 type BigCatAllOf struct {
 	Kind *string `json:"kind,omitempty"`
@@ -69,11 +72,19 @@ func (o *BigCatAllOf) SetKind(v string) {
 }
 
 func (o BigCatAllOf) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o BigCatAllOf) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Kind) {
 		toSerialize["kind"] = o.Kind
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableBigCatAllOf struct {

samples/client/petstore/go/go-petstore/model_capitalization.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Capitalization type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Capitalization{}
+
 // Capitalization struct for Capitalization
 type Capitalization struct {
 	SmallCamel *string `json:"smallCamel,omitempty"`
@@ -235,6 +238,14 @@ func (o *Capitalization) SetATT_NAME(v string) {
 }
 
 func (o Capitalization) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Capitalization) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.SmallCamel) {
 		toSerialize["smallCamel"] = o.SmallCamel
@@ -254,7 +265,7 @@ func (o Capitalization) MarshalJSON() ([]byte, error) {
 	if !isNil(o.ATT_NAME) {
 		toSerialize["ATT_NAME"] = o.ATT_NAME
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableCapitalization struct {

samples/client/petstore/go/go-petstore/model_cat.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Cat type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Cat{}
+
 // Cat struct for Cat
 type Cat struct {
 	Animal
@@ -73,19 +76,27 @@ func (o *Cat) SetDeclawed(v bool) {
 }
 
 func (o Cat) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Cat) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	serializedAnimal, errAnimal := json.Marshal(o.Animal)
 	if errAnimal != nil {
-		return []byte{}, errAnimal
+		return map[string]interface{}{}, errAnimal
 	}
 	errAnimal = json.Unmarshal([]byte(serializedAnimal), &toSerialize)
 	if errAnimal != nil {
-		return []byte{}, errAnimal
+		return map[string]interface{}{}, errAnimal
 	}
 	if !isNil(o.Declawed) {
 		toSerialize["declawed"] = o.Declawed
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableCat struct {

samples/client/petstore/go/go-petstore/model_cat_all_of.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the CatAllOf type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &CatAllOf{}
+
 // CatAllOf struct for CatAllOf
 type CatAllOf struct {
 	Declawed *bool `json:"declawed,omitempty"`
@@ -69,11 +72,19 @@ func (o *CatAllOf) SetDeclawed(v bool) {
 }
 
 func (o CatAllOf) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o CatAllOf) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Declawed) {
 		toSerialize["declawed"] = o.Declawed
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableCatAllOf struct {

samples/client/petstore/go/go-petstore/model_category.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Category type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Category{}
+
 // Category struct for Category
 type Category struct {
 	Id *int64 `json:"id,omitempty"`
@@ -97,14 +100,20 @@ func (o *Category) SetName(v string) {
 }
 
 func (o Category) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Category) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Id) {
 		toSerialize["id"] = o.Id
 	}
-	if true {
 	toSerialize["name"] = o.Name
-	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableCategory struct {

samples/client/petstore/go/go-petstore/model_class_model.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ClassModel type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ClassModel{}
+
 // ClassModel Model for testing model with \"_class\" property
 type ClassModel struct {
 	Class *string `json:"_class,omitempty"`
@@ -69,11 +72,19 @@ func (o *ClassModel) SetClass(v string) {
 }
 
 func (o ClassModel) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ClassModel) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Class) {
 		toSerialize["_class"] = o.Class
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableClassModel struct {

samples/client/petstore/go/go-petstore/model_client.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Client type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Client{}
+
 // Client struct for Client
 type Client struct {
 	Client *string `json:"client,omitempty"`
@@ -69,11 +72,19 @@ func (o *Client) SetClient(v string) {
 }
 
 func (o Client) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Client) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Client) {
 		toSerialize["client"] = o.Client
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableClient struct {

samples/client/petstore/go/go-petstore/model_dog.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Dog type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Dog{}
+
 // Dog struct for Dog
 type Dog struct {
 	Animal
@@ -73,19 +76,27 @@ func (o *Dog) SetBreed(v string) {
 }
 
 func (o Dog) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Dog) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	serializedAnimal, errAnimal := json.Marshal(o.Animal)
 	if errAnimal != nil {
-		return []byte{}, errAnimal
+		return map[string]interface{}{}, errAnimal
 	}
 	errAnimal = json.Unmarshal([]byte(serializedAnimal), &toSerialize)
 	if errAnimal != nil {
-		return []byte{}, errAnimal
+		return map[string]interface{}{}, errAnimal
 	}
 	if !isNil(o.Breed) {
 		toSerialize["breed"] = o.Breed
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableDog struct {

samples/client/petstore/go/go-petstore/model_dog_all_of.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the DogAllOf type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &DogAllOf{}
+
 // DogAllOf struct for DogAllOf
 type DogAllOf struct {
 	Breed *string `json:"breed,omitempty"`
@@ -69,11 +72,19 @@ func (o *DogAllOf) SetBreed(v string) {
 }
 
 func (o DogAllOf) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o DogAllOf) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Breed) {
 		toSerialize["breed"] = o.Breed
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableDogAllOf struct {

samples/client/petstore/go/go-petstore/model_enum_arrays.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the EnumArrays type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &EnumArrays{}
+
 // EnumArrays struct for EnumArrays
 type EnumArrays struct {
 	JustSymbol *string `json:"just_symbol,omitempty"`
@@ -102,6 +105,14 @@ func (o *EnumArrays) SetArrayEnum(v []string) {
 }
 
 func (o EnumArrays) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o EnumArrays) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.JustSymbol) {
 		toSerialize["just_symbol"] = o.JustSymbol
@@ -109,7 +120,7 @@ func (o EnumArrays) MarshalJSON() ([]byte, error) {
 	if !isNil(o.ArrayEnum) {
 		toSerialize["array_enum"] = o.ArrayEnum
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableEnumArrays struct {

samples/client/petstore/go/go-petstore/model_enum_test_.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the EnumTest type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &EnumTest{}
+
 // EnumTest struct for EnumTest
 type EnumTest struct {
 	EnumString *string `json:"enum_string,omitempty"`
@@ -194,13 +197,19 @@ func (o *EnumTest) SetOuterEnum(v OuterEnum) {
 }
 
 func (o EnumTest) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o EnumTest) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.EnumString) {
 		toSerialize["enum_string"] = o.EnumString
 	}
-	if true {
 	toSerialize["enum_string_required"] = o.EnumStringRequired
-	}
 	if !isNil(o.EnumInteger) {
 		toSerialize["enum_integer"] = o.EnumInteger
 	}
@@ -210,7 +219,7 @@ func (o EnumTest) MarshalJSON() ([]byte, error) {
 	if !isNil(o.OuterEnum) {
 		toSerialize["outerEnum"] = o.OuterEnum
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableEnumTest struct {

samples/client/petstore/go/go-petstore/model_file.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the File type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &File{}
+
 // File Must be named `File` for test.
 type File struct {
 	// Test capitalization
@@ -70,11 +73,19 @@ func (o *File) SetSourceURI(v string) {
 }
 
 func (o File) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o File) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.SourceURI) {
 		toSerialize["sourceURI"] = o.SourceURI
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableFile struct {

samples/client/petstore/go/go-petstore/model_file_schema_test_class.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the FileSchemaTestClass type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &FileSchemaTestClass{}
+
 // FileSchemaTestClass struct for FileSchemaTestClass
 type FileSchemaTestClass struct {
 	File *File `json:"file,omitempty"`
@@ -102,6 +105,14 @@ func (o *FileSchemaTestClass) SetFiles(v []File) {
 }
 
 func (o FileSchemaTestClass) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o FileSchemaTestClass) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.File) {
 		toSerialize["file"] = o.File
@@ -109,7 +120,7 @@ func (o FileSchemaTestClass) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Files) {
 		toSerialize["files"] = o.Files
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableFileSchemaTestClass struct {

samples/client/petstore/go/go-petstore/model_format_test_.go

@@ -16,6 +16,9 @@ import (
 	"time"
 )
 
+// checks if the FormatTest type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &FormatTest{}
+
 // FormatTest struct for FormatTest
 type FormatTest struct {
 	Integer *int32 `json:"integer,omitempty"`
@@ -472,6 +475,14 @@ func (o *FormatTest) SetBigDecimal(v float64) {
 }
 
 func (o FormatTest) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o FormatTest) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Integer) {
 		toSerialize["integer"] = o.Integer
@@ -482,9 +493,7 @@ func (o FormatTest) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Int64) {
 		toSerialize["int64"] = o.Int64
 	}
-	if true {
 	toSerialize["number"] = o.Number
-	}
 	if !isNil(o.Float) {
 		toSerialize["float"] = o.Float
 	}
@@ -494,28 +503,22 @@ func (o FormatTest) MarshalJSON() ([]byte, error) {
 	if !isNil(o.String) {
 		toSerialize["string"] = o.String
 	}
-	if true {
 	toSerialize["byte"] = o.Byte
-	}
 	if !isNil(o.Binary) {
 		toSerialize["binary"] = o.Binary
 	}
-	if true {
 	toSerialize["date"] = o.Date
-	}
 	if !isNil(o.DateTime) {
 		toSerialize["dateTime"] = o.DateTime
 	}
 	if !isNil(o.Uuid) {
 		toSerialize["uuid"] = o.Uuid
 	}
-	if true {
 	toSerialize["password"] = o.Password
-	}
 	if !isNil(o.BigDecimal) {
 		toSerialize["BigDecimal"] = o.BigDecimal
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableFormatTest struct {

samples/client/petstore/go/go-petstore/model_has_only_read_only.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the HasOnlyReadOnly type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &HasOnlyReadOnly{}
+
 // HasOnlyReadOnly struct for HasOnlyReadOnly
 type HasOnlyReadOnly struct {
 	Bar *string `json:"bar,omitempty"`
@@ -102,6 +105,14 @@ func (o *HasOnlyReadOnly) SetFoo(v string) {
 }
 
 func (o HasOnlyReadOnly) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o HasOnlyReadOnly) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Bar) {
 		toSerialize["bar"] = o.Bar
@@ -109,7 +120,7 @@ func (o HasOnlyReadOnly) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Foo) {
 		toSerialize["foo"] = o.Foo
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableHasOnlyReadOnly struct {

samples/client/petstore/go/go-petstore/model_list.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the List type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &List{}
+
 // List struct for List
 type List struct {
 	Var123List *string `json:"123-list,omitempty"`
@@ -69,11 +72,19 @@ func (o *List) SetVar123List(v string) {
 }
 
 func (o List) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o List) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Var123List) {
 		toSerialize["123-list"] = o.Var123List
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableList struct {

samples/client/petstore/go/go-petstore/model_map_test_.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the MapTest type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &MapTest{}
+
 // MapTest struct for MapTest
 type MapTest struct {
 	MapMapOfString *map[string]map[string]string `json:"map_map_of_string,omitempty"`
@@ -168,6 +171,14 @@ func (o *MapTest) SetIndirectMap(v map[string]bool) {
 }
 
 func (o MapTest) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o MapTest) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.MapMapOfString) {
 		toSerialize["map_map_of_string"] = o.MapMapOfString
@@ -181,7 +192,7 @@ func (o MapTest) MarshalJSON() ([]byte, error) {
 	if !isNil(o.IndirectMap) {
 		toSerialize["indirect_map"] = o.IndirectMap
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableMapTest struct {

samples/client/petstore/go/go-petstore/model_mixed_properties_and_additional_properties_class.go

@@ -15,6 +15,9 @@ import (
 	"time"
 )
 
+// checks if the MixedPropertiesAndAdditionalPropertiesClass type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &MixedPropertiesAndAdditionalPropertiesClass{}
+
 // MixedPropertiesAndAdditionalPropertiesClass struct for MixedPropertiesAndAdditionalPropertiesClass
 type MixedPropertiesAndAdditionalPropertiesClass struct {
 	Uuid *string `json:"uuid,omitempty"`
@@ -136,6 +139,14 @@ func (o *MixedPropertiesAndAdditionalPropertiesClass) SetMap(v map[string]Animal
 }
 
 func (o MixedPropertiesAndAdditionalPropertiesClass) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o MixedPropertiesAndAdditionalPropertiesClass) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Uuid) {
 		toSerialize["uuid"] = o.Uuid
@@ -146,7 +157,7 @@ func (o MixedPropertiesAndAdditionalPropertiesClass) MarshalJSON() ([]byte, erro
 	if !isNil(o.Map) {
 		toSerialize["map"] = o.Map
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableMixedPropertiesAndAdditionalPropertiesClass struct {

samples/client/petstore/go/go-petstore/model_name.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Name type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Name{}
+
 // Name Model for testing model name same as property name
 type Name struct {
 	Name int32 `json:"name"`
@@ -161,10 +164,16 @@ func (o *Name) SetVar123Number(v int32) {
 }
 
 func (o Name) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if true {
-		toSerialize["name"] = o.Name
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
 	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Name) ToMap() (map[string]interface{}, error) {
+	toSerialize := map[string]interface{}{}
+	toSerialize["name"] = o.Name
 	if !isNil(o.SnakeCase) {
 		toSerialize["snake_case"] = o.SnakeCase
 	}
@@ -174,7 +183,7 @@ func (o Name) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Var123Number) {
 		toSerialize["123Number"] = o.Var123Number
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableName struct {

samples/client/petstore/go/go-petstore/model_number_only.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the NumberOnly type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &NumberOnly{}
+
 // NumberOnly struct for NumberOnly
 type NumberOnly struct {
 	JustNumber *float32 `json:"JustNumber,omitempty"`
@@ -69,11 +72,19 @@ func (o *NumberOnly) SetJustNumber(v float32) {
 }
 
 func (o NumberOnly) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o NumberOnly) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.JustNumber) {
 		toSerialize["JustNumber"] = o.JustNumber
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableNumberOnly struct {

samples/client/petstore/go/go-petstore/model_order.go

@@ -15,6 +15,9 @@ import (
 	"time"
 )
 
+// checks if the Order type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Order{}
+
 // Order struct for Order
 type Order struct {
 	Id *int64 `json:"id,omitempty"`
@@ -240,6 +243,14 @@ func (o *Order) SetComplete(v bool) {
 }
 
 func (o Order) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Order) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Id) {
 		toSerialize["id"] = o.Id
@@ -259,7 +270,7 @@ func (o Order) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Complete) {
 		toSerialize["complete"] = o.Complete
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableOrder struct {

samples/client/petstore/go/go-petstore/model_outer_composite.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the OuterComposite type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &OuterComposite{}
+
 // OuterComposite struct for OuterComposite
 type OuterComposite struct {
 	MyNumber *float32 `json:"my_number,omitempty"`
@@ -135,6 +138,14 @@ func (o *OuterComposite) SetMyBoolean(v bool) {
 }
 
 func (o OuterComposite) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o OuterComposite) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.MyNumber) {
 		toSerialize["my_number"] = o.MyNumber
@@ -145,7 +156,7 @@ func (o OuterComposite) MarshalJSON() ([]byte, error) {
 	if !isNil(o.MyBoolean) {
 		toSerialize["my_boolean"] = o.MyBoolean
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableOuterComposite struct {

samples/client/petstore/go/go-petstore/model_pet.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Pet type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Pet{}
+
 // Pet struct for Pet
 type Pet struct {
 	Id *int64 `json:"id,omitempty"`
@@ -221,6 +224,14 @@ func (o *Pet) SetStatus(v string) {
 }
 
 func (o Pet) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Pet) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Id) {
 		toSerialize["id"] = o.Id
@@ -228,19 +239,15 @@ func (o Pet) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Category) {
 		toSerialize["category"] = o.Category
 	}
-	if true {
 	toSerialize["name"] = o.Name
-	}
-	if true {
 	toSerialize["photoUrls"] = o.PhotoUrls
-	}
 	if !isNil(o.Tags) {
 		toSerialize["tags"] = o.Tags
 	}
 	if !isNil(o.Status) {
 		toSerialize["status"] = o.Status
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullablePet struct {

samples/client/petstore/go/go-petstore/model_read_only_first.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ReadOnlyFirst type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ReadOnlyFirst{}
+
 // ReadOnlyFirst struct for ReadOnlyFirst
 type ReadOnlyFirst struct {
 	Bar *string `json:"bar,omitempty"`
@@ -102,6 +105,14 @@ func (o *ReadOnlyFirst) SetBaz(v string) {
 }
 
 func (o ReadOnlyFirst) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ReadOnlyFirst) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Bar) {
 		toSerialize["bar"] = o.Bar
@@ -109,7 +120,7 @@ func (o ReadOnlyFirst) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Baz) {
 		toSerialize["baz"] = o.Baz
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableReadOnlyFirst struct {

samples/client/petstore/go/go-petstore/model_return.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Return type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Return{}
+
 // Return Model for testing reserved words
 type Return struct {
 	Return *int32 `json:"return,omitempty"`
@@ -69,11 +72,19 @@ func (o *Return) SetReturn(v int32) {
 }
 
 func (o Return) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Return) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Return) {
 		toSerialize["return"] = o.Return
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableReturn struct {

samples/client/petstore/go/go-petstore/model_special_model_name.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the SpecialModelName type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &SpecialModelName{}
+
 // SpecialModelName struct for SpecialModelName
 type SpecialModelName struct {
 	SpecialPropertyName *int64 `json:"$special[property.name],omitempty"`
@@ -69,11 +72,19 @@ func (o *SpecialModelName) SetSpecialPropertyName(v int64) {
 }
 
 func (o SpecialModelName) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o SpecialModelName) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.SpecialPropertyName) {
 		toSerialize["$special[property.name]"] = o.SpecialPropertyName
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableSpecialModelName struct {

samples/client/petstore/go/go-petstore/model_tag.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Tag type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Tag{}
+
 // Tag struct for Tag
 type Tag struct {
 	Id *int64 `json:"id,omitempty"`
@@ -102,6 +105,14 @@ func (o *Tag) SetName(v string) {
 }
 
 func (o Tag) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Tag) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Id) {
 		toSerialize["id"] = o.Id
@@ -109,7 +120,7 @@ func (o Tag) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Name) {
 		toSerialize["name"] = o.Name
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableTag struct {

samples/client/petstore/go/go-petstore/model_type_holder_default.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the TypeHolderDefault type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &TypeHolderDefault{}
+
 // TypeHolderDefault struct for TypeHolderDefault
 type TypeHolderDefault struct {
 	StringItem string `json:"string_item"`
@@ -170,25 +173,23 @@ func (o *TypeHolderDefault) SetArrayItem(v []int32) {
 }
 
 func (o TypeHolderDefault) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if true {
-		toSerialize["string_item"] = o.StringItem
-	}
-	if true {
-		toSerialize["number_item"] = o.NumberItem
-	}
-	if true {
-		toSerialize["integer_item"] = o.IntegerItem
-	}
-	if true {
-		toSerialize["bool_item"] = o.BoolItem
-	}
-	if true {
-		toSerialize["array_item"] = o.ArrayItem
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
 	}
 	return json.Marshal(toSerialize)
 }
 
+func (o TypeHolderDefault) ToMap() (map[string]interface{}, error) {
+	toSerialize := map[string]interface{}{}
+	toSerialize["string_item"] = o.StringItem
+	toSerialize["number_item"] = o.NumberItem
+	toSerialize["integer_item"] = o.IntegerItem
+	toSerialize["bool_item"] = o.BoolItem
+	toSerialize["array_item"] = o.ArrayItem
+	return toSerialize, nil
+}
+
 type NullableTypeHolderDefault struct {
 	value *TypeHolderDefault
 	isSet bool

samples/client/petstore/go/go-petstore/model_type_holder_example.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the TypeHolderExample type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &TypeHolderExample{}
+
 // TypeHolderExample struct for TypeHolderExample
 type TypeHolderExample struct {
 	StringItem string `json:"string_item"`
@@ -192,28 +195,24 @@ func (o *TypeHolderExample) SetArrayItem(v []int32) {
 }
 
 func (o TypeHolderExample) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if true {
-		toSerialize["string_item"] = o.StringItem
-	}
-	if true {
-		toSerialize["number_item"] = o.NumberItem
-	}
-	if true {
-		toSerialize["float_item"] = o.FloatItem
-	}
-	if true {
-		toSerialize["integer_item"] = o.IntegerItem
-	}
-	if true {
-		toSerialize["bool_item"] = o.BoolItem
-	}
-	if true {
-		toSerialize["array_item"] = o.ArrayItem
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
 	}
 	return json.Marshal(toSerialize)
 }
 
+func (o TypeHolderExample) ToMap() (map[string]interface{}, error) {
+	toSerialize := map[string]interface{}{}
+	toSerialize["string_item"] = o.StringItem
+	toSerialize["number_item"] = o.NumberItem
+	toSerialize["float_item"] = o.FloatItem
+	toSerialize["integer_item"] = o.IntegerItem
+	toSerialize["bool_item"] = o.BoolItem
+	toSerialize["array_item"] = o.ArrayItem
+	return toSerialize, nil
+}
+
 type NullableTypeHolderExample struct {
 	value *TypeHolderExample
 	isSet bool

samples/client/petstore/go/go-petstore/model_user.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the User type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &User{}
+
 // User struct for User
 type User struct {
 	Id *int64 `json:"id,omitempty"`
@@ -301,6 +304,14 @@ func (o *User) SetUserStatus(v int32) {
 }
 
 func (o User) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o User) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Id) {
 		toSerialize["id"] = o.Id
@@ -326,7 +337,7 @@ func (o User) MarshalJSON() ([]byte, error) {
 	if !isNil(o.UserStatus) {
 		toSerialize["userStatus"] = o.UserStatus
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableUser struct {

samples/client/petstore/go/go-petstore/model_xml_item.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the XmlItem type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &XmlItem{}
+
 // XmlItem struct for XmlItem
 type XmlItem struct {
 	AttributeString *string `json:"attribute_string,omitempty"`
@@ -993,6 +996,14 @@ func (o *XmlItem) SetPrefixNsWrappedArray(v []int32) {
 }
 
 func (o XmlItem) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o XmlItem) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.AttributeString) {
 		toSerialize["attribute_string"] = o.AttributeString
@@ -1081,7 +1092,7 @@ func (o XmlItem) MarshalJSON() ([]byte, error) {
 	if !isNil(o.PrefixNsWrappedArray) {
 		toSerialize["prefix_ns_wrapped_array"] = o.PrefixNsWrappedArray
 	}
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 type NullableXmlItem struct {

samples/client/petstore/go/go-petstore/utils.go

@@ -341,3 +341,7 @@ func isNil(i interface{}) bool {
 	}
 	return false
 }
+
+type MappedNullable interface {
+	ToMap() (map[string]interface{}, error)
+}

samples/client/petstore/go/pet_api_test.go

@@ -111,7 +111,7 @@ 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, "available", "Pet status should be `pending`")
+					assert.Equal("available", *resp[i].Status, "Pet status should be `available`")
 					found = true
 				}
 			}

samples/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 {

samples/openapi3/client/extensions/x-auth-id-alias/go-experimental/client.go

@@ -39,6 +39,8 @@ import (
 var (
 	jsonCheck = regexp.MustCompile(`(?i:(?:application|text)/(?:vnd\.[^;]+\+)?json)`)
 	xmlCheck  = regexp.MustCompile(`(?i:(?:application|text)/xml)`)
+    queryParamSplit = regexp.MustCompile(`(^|&)([^&]+)`)
+    queryDescape    = strings.NewReplacer( "%5B", "[", "%5D", "]" )
 )
 
 // APIClient manages communication with the OpenAPI Extension x-auth-id-alias API v1.0.0
@@ -125,29 +127,102 @@ func typeCheckParameter(obj interface{}, expected string, name string) error {
 	return nil
 }
 
-// parameterToString convert interface{} parameters to string, using a delimiter if format is provided.
-func parameterToString(obj interface{}, collectionFormat string) string {
-	var delimiter string
-
-	switch collectionFormat {
-	case "pipes":
-		delimiter = "|"
-	case "ssv":
-		delimiter = " "
-	case "tsv":
-		delimiter = "\t"
-	case "csv":
-		delimiter = ","
-	}
-
-	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)
-	}
-
+func parameterValueToString( obj interface{}, key string ) string {
+    if reflect.TypeOf(obj).Kind() != reflect.Ptr {
         return fmt.Sprintf("%v", obj)
     }
+    var param,ok = obj.(MappedNullable)
+    if !ok {
+        return ""
+    }
+    dataMap,err := param.ToMap()
+    if err != nil {
+        return ""
+    }
+    return fmt.Sprintf("%v", dataMap[key])
+}
+
+// parameterAddToQuery adds the provided object to the url query supporting deep object syntax
+func parameterAddToQuery(queryParams interface{}, keyPrefix string, obj interface{}, collectionType string) {
+    var v = reflect.ValueOf(obj)
+    var value = ""
+    if v == reflect.ValueOf(nil) {
+        value = "null"
+    } else {
+        switch v.Kind() {
+			case reflect.Invalid:
+				value = "invalid"
+
+			case reflect.Struct:
+				if t,ok := obj.(MappedNullable); ok {
+					dataMap,err := t.ToMap()
+					if err != nil {
+						return
+					}
+					parameterAddToQuery(queryParams, keyPrefix, dataMap, collectionType)
+					return
+				}
+				if t, ok := obj.(time.Time); ok {
+					parameterAddToQuery(queryParams, keyPrefix, t.Format(time.RFC3339), collectionType)
+					return
+				}
+				value = v.Type().String() + " value"
+			case reflect.Slice:
+				var indValue = reflect.ValueOf(obj)
+				if indValue == reflect.ValueOf(nil) {
+					return
+				}
+				var lenIndValue = indValue.Len()
+				for i:=0;i<lenIndValue;i++ {
+					var arrayValue = indValue.Index(i)
+					parameterAddToQuery(queryParams, keyPrefix, arrayValue.Interface(), collectionType)
+				}
+				return
+
+			case reflect.Map:
+				var indValue = reflect.ValueOf(obj)
+				if indValue == reflect.ValueOf(nil) {
+					return
+				}
+				iter := indValue.MapRange()
+				for iter.Next() {
+					k,v := iter.Key(), iter.Value()
+					parameterAddToQuery(queryParams, fmt.Sprintf("%s[%s]", keyPrefix, k.String()), v.Interface(), collectionType)
+				}
+				return
+
+			case reflect.Interface:
+				fallthrough
+            case reflect.Ptr:
+				parameterAddToQuery(queryParams, keyPrefix, v.Elem().Interface(), collectionType)
+                return
+
+            case reflect.Int, reflect.Int8, reflect.Int16,
+                reflect.Int32, reflect.Int64:
+                value = strconv.FormatInt(v.Int(), 10)
+            case reflect.Uint, reflect.Uint8, reflect.Uint16,
+                reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+                value = strconv.FormatUint(v.Uint(), 10)
+            case reflect.Float32, reflect.Float64:
+                value = strconv.FormatFloat(v.Float(), 'g', -1, 32)
+            case reflect.Bool:
+                value = strconv.FormatBool(v.Bool())
+            case reflect.String:
+                value = v.String()
+            default:
+                value = v.Type().String() + " value"
+        }
+    }
+
+    switch valuesMap := queryParams.(type) {
+        case url.Values:
+            valuesMap.Add( keyPrefix, value )
+            break
+        case map[string]string:
+            valuesMap[keyPrefix] = value
+            break
+    }
+}
 
 // helper for converting interface{} parameters to json strings
 func parameterToJson(obj interface{}) (string, error) {
@@ -298,7 +373,11 @@ func (c *APIClient) prepareRequest(
 	}
 
 	// Encode the parameters.
-	url.RawQuery = query.Encode()
+    url.RawQuery = queryParamSplit.ReplaceAllStringFunc(query.Encode(), func(s string) string {
+        pieces := strings.Split(s, "=")
+        pieces[0] = queryDescape.Replace(pieces[0])
+        return strings.Join(pieces, "=")
+    })
 
 	// Generate a new request
 	if body != nil {

samples/openapi3/client/extensions/x-auth-id-alias/go-experimental/utils.go

@@ -341,3 +341,7 @@ func isNil(i interface{}) bool {
 	}
 	return false
 }
+
+type MappedNullable interface {
+	ToMap() (map[string]interface{}, error)
+}

samples/openapi3/client/petstore/go/fake_api_test.go

@@ -2,11 +2,16 @@ package main
 
 import (
 	"context"
+	"github.com/stretchr/testify/assert"
 	"testing"
 
 	sw "go-petstore"
 )
 
+const (
+	deepObjectURL = `/v2/fake/deep_object_test?inputOptions[F1]=1&inputOptions[F2]=teststring&inputOptions[F3]=null&inputOptions[id]=1&inputOptions[name]=TestCat&test_pet[F1]=1&test_pet[F2]=teststring&test_pet[F3]=null&test_pet[id]=1&test_pet[name]=Test&test_pet[photoUrls]=http%3A%2F%2Flocalhost&test_pet[tags][F1]=1&test_pet[tags][F2]=teststring&test_pet[tags][F3]=null&test_pet[tags][id]=2&test_pet[tags][name]=tag1`
+)
+
 // TestPutBodyWithFileSchema ensures a model with the name 'File'
 // gets converted properly to the petstore.File struct vs. *os.File
 // as specified in typeMapping for 'File'.
@@ -26,3 +31,50 @@ func TestPutBodyWithFileSchema(t *testing.T) {
 		t.Log(r)
 	}
 }
+
+func TestQueryDeepObject(t *testing.T) {
+	req := client.FakeApi.TestQueryDeepObject(context.Background())
+
+	var id = int64(1)
+	var idTag1 = int64(2)
+	var nameTag1 = "tag1"
+	req = req.TestPet(sw.Pet{
+		Id: &id,
+		Name: "Test",
+		PhotoUrls: []string{ "http://localhost" },
+		Tags: []sw.Tag{
+			{
+				Id: &idTag1,
+				Name: &nameTag1,
+				AdditionalProperties: map[string]interface{}{
+					"F1": 1,
+					"F2": "teststring",
+					"F3": nil,
+				},
+			},
+		},
+		AdditionalProperties: map[string]interface{}{
+			"F1": 1,
+			"F2": "teststring",
+			"F3": nil,
+		},
+	})
+	var idcat = int64(1)
+	req = req.InputOptions(sw.Category{
+		Id: &idcat,
+		Name: "TestCat",
+		AdditionalProperties: map[string]interface{}{
+			"F1": 1,
+			"F2": "teststring",
+			"F3": nil,
+		},
+	})
+
+	r, _ := req.Execute()
+
+	var expectedDeepObjectURL = testScheme + "://" + testHost + deepObjectURL
+
+	assert.Equal(t,
+		expectedDeepObjectURL,
+		r.Request.URL.String() )
+}

samples/openapi3/client/petstore/go/go-petstore/README.md

@@ -93,6 +93,7 @@ Class | Method | HTTP request | Description
 *FakeApi* | [**TestGroupParameters**](docs/FakeApi.md#testgroupparameters) | **Delete** /fake | Fake endpoint to test group parameters (optional)
 *FakeApi* | [**TestInlineAdditionalProperties**](docs/FakeApi.md#testinlineadditionalproperties) | **Post** /fake/inline-additionalProperties | test inline additionalProperties
 *FakeApi* | [**TestJsonFormData**](docs/FakeApi.md#testjsonformdata) | **Get** /fake/jsonFormData | test json serialization of form data
+*FakeApi* | [**TestQueryDeepObject**](docs/FakeApi.md#testquerydeepobject) | **Get** /fake/deep_object_test | 
 *FakeApi* | [**TestQueryParameterCollectionFormat**](docs/FakeApi.md#testqueryparametercollectionformat) | **Put** /fake/test-query-parameters | 
 *FakeApi* | [**TestUniqueItemsHeaderAndQueryParameterCollectionFormat**](docs/FakeApi.md#testuniqueitemsheaderandqueryparametercollectionformat) | **Put** /fake/test-unique-parameters | 
 *FakeClassnameTags123Api* | [**TestClassname**](docs/FakeClassnameTags123Api.md#testclassname) | **Patch** /fake_classname_test | To test class name in snake case

samples/openapi3/client/petstore/go/go-petstore/api/openapi.yaml

@@ -669,7 +669,7 @@ paths:
           description: Something wrong
         "5XX":
           content:
-            applicatino/json:
+            application/json:
               schema:
                 $ref: '#/components/schemas/OuterNumber'
           description: Something wrong
@@ -1116,6 +1116,29 @@ paths:
       summary: Health check endpoint
       tags:
       - fake
+  /fake/deep_object_test:
+    get:
+      operationId: test_query_deep_object
+      parameters:
+      - explode: true
+        in: query
+        name: test_pet
+        required: false
+        schema:
+          $ref: '#/components/schemas/Pet'
+        style: deepObject
+      - explode: true
+        in: query
+        name: inputOptions
+        required: false
+        schema:
+          $ref: '#/components/schemas/Category'
+        style: deepObject
+      responses:
+        "200":
+          description: OK
+      tags:
+      - fake
 components:
   requestBodies:
     UserArray:

samples/openapi3/client/petstore/go/go-petstore/api_fake.go

@@ -199,6 +199,17 @@ type FakeApi interface {
 	// TestJsonFormDataExecute executes the request
 	TestJsonFormDataExecute(r ApiTestJsonFormDataRequest) (*http.Response, error)
 
+	/*
+	TestQueryDeepObject Method for TestQueryDeepObject
+
+	@param ctx context.Context - for authentication, logging, cancellation, deadlines, tracing, etc. Passed from http.Request or context.Background().
+	@return ApiTestQueryDeepObjectRequest
+	*/
+	TestQueryDeepObject(ctx context.Context) ApiTestQueryDeepObjectRequest
+
+	// TestQueryDeepObjectExecute executes the request
+	TestQueryDeepObjectExecute(r ApiTestQueryDeepObjectRequest) (*http.Response, error)
+
 	/*
 	TestQueryParameterCollectionFormat Method for TestQueryParameterCollectionFormat
 
@@ -917,7 +928,7 @@ func (a *FakeApiService) TestBodyWithQueryParamsExecute(r ApiTestBodyWithQueryPa
 		return nil, reportError("user is required and must be specified")
 	}
 
-	localVarQueryParams.Add("query", parameterToString(*r.query, ""))
+	parameterAddToQuery(localVarQueryParams, "query", r.query, "")
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{"application/json"}
 
@@ -1263,24 +1274,24 @@ func (a *FakeApiService) TestEndpointParametersExecute(r ApiTestEndpointParamete
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.integer != nil {
-		localVarFormParams.Add("integer", parameterToString(*r.integer, ""))
+		parameterAddToQuery(localVarFormParams, "integer", r.integer, "")
 	}
 	if r.int32_ != nil {
-		localVarFormParams.Add("int32", parameterToString(*r.int32_, ""))
+		parameterAddToQuery(localVarFormParams, "int32", r.int32_, "")
 	}
 	if r.int64_ != nil {
-		localVarFormParams.Add("int64", parameterToString(*r.int64_, ""))
+		parameterAddToQuery(localVarFormParams, "int64", r.int64_, "")
 	}
-	localVarFormParams.Add("number", parameterToString(*r.number, ""))
+	parameterAddToQuery(localVarFormParams, "number", r.number, "")
 	if r.float != nil {
-		localVarFormParams.Add("float", parameterToString(*r.float, ""))
+		parameterAddToQuery(localVarFormParams, "float", r.float, "")
 	}
-	localVarFormParams.Add("double", parameterToString(*r.double, ""))
+	parameterAddToQuery(localVarFormParams, "double", r.double, "")
 	if r.string_ != nil {
-		localVarFormParams.Add("string", parameterToString(*r.string_, ""))
+		parameterAddToQuery(localVarFormParams, "string", r.string_, "")
 	}
-	localVarFormParams.Add("pattern_without_delimiter", parameterToString(*r.patternWithoutDelimiter, ""))
-	localVarFormParams.Add("byte", parameterToString(*r.byte_, ""))
+	parameterAddToQuery(localVarFormParams, "pattern_without_delimiter", r.patternWithoutDelimiter, "")
+	parameterAddToQuery(localVarFormParams, "byte", r.byte_, "")
 	var binaryLocalVarFormFileName string
 	var binaryLocalVarFileName     string
 	var binaryLocalVarFileBytes    []byte
@@ -1299,16 +1310,16 @@ func (a *FakeApiService) TestEndpointParametersExecute(r ApiTestEndpointParamete
 	}
 	formFiles = append(formFiles, formFile{fileBytes: binaryLocalVarFileBytes, fileName: binaryLocalVarFileName, formFileName: binaryLocalVarFormFileName})
 	if r.date != nil {
-		localVarFormParams.Add("date", parameterToString(*r.date, ""))
+		parameterAddToQuery(localVarFormParams, "date", r.date, "")
 	}
 	if r.dateTime != nil {
-		localVarFormParams.Add("dateTime", parameterToString(*r.dateTime, ""))
+		parameterAddToQuery(localVarFormParams, "dateTime", r.dateTime, "")
 	}
 	if r.password != nil {
-		localVarFormParams.Add("password", parameterToString(*r.password, ""))
+		parameterAddToQuery(localVarFormParams, "password", r.password, "")
 	}
 	if r.callback != nil {
-		localVarFormParams.Add("callback", parameterToString(*r.callback, ""))
+		parameterAddToQuery(localVarFormParams, "callback", r.callback, "")
 	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
@@ -1442,20 +1453,20 @@ func (a *FakeApiService) TestEnumParametersExecute(r ApiTestEnumParametersReques
 		if reflect.TypeOf(t).Kind() == reflect.Slice {
 			s := reflect.ValueOf(t)
 			for i := 0; i < s.Len(); i++ {
-				localVarQueryParams.Add("enum_query_string_array", parameterToString(s.Index(i), "multi"))
+				parameterAddToQuery(localVarQueryParams, "enum_query_string_array", s.Index(i), "multi")
 			}
 		} else {
-			localVarQueryParams.Add("enum_query_string_array", parameterToString(t, "multi"))
+			parameterAddToQuery(localVarQueryParams, "enum_query_string_array", t, "multi")
 		}
 	}
 	if r.enumQueryString != nil {
-		localVarQueryParams.Add("enum_query_string", parameterToString(*r.enumQueryString, ""))
+	    parameterAddToQuery(localVarQueryParams, "enum_query_string", r.enumQueryString, "")
 	}
 	if r.enumQueryInteger != nil {
-		localVarQueryParams.Add("enum_query_integer", parameterToString(*r.enumQueryInteger, ""))
+	    parameterAddToQuery(localVarQueryParams, "enum_query_integer", r.enumQueryInteger, "")
 	}
 	if r.enumQueryDouble != nil {
-		localVarQueryParams.Add("enum_query_double", parameterToString(*r.enumQueryDouble, ""))
+	    parameterAddToQuery(localVarQueryParams, "enum_query_double", r.enumQueryDouble, "")
 	}
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{"application/x-www-form-urlencoded"}
@@ -1475,16 +1486,16 @@ func (a *FakeApiService) TestEnumParametersExecute(r ApiTestEnumParametersReques
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.enumHeaderStringArray != nil {
-		localVarHeaderParams["enum_header_string_array"] = parameterToString(*r.enumHeaderStringArray, "csv")
+		parameterAddToQuery(localVarQueryParams, "enum_header_string_array", r.enumHeaderStringArray, "csv")
 	}
 	if r.enumHeaderString != nil {
-		localVarHeaderParams["enum_header_string"] = parameterToString(*r.enumHeaderString, "")
+		parameterAddToQuery(localVarQueryParams, "enum_header_string", r.enumHeaderString, "")
 	}
 	if r.enumFormStringArray != nil {
-		localVarFormParams.Add("enum_form_string_array", parameterToString(*r.enumFormStringArray, "csv"))
+		parameterAddToQuery(localVarFormParams, "enum_form_string_array", r.enumFormStringArray, "csv")
 	}
 	if r.enumFormString != nil {
-		localVarFormParams.Add("enum_form_string", parameterToString(*r.enumFormString, ""))
+		parameterAddToQuery(localVarFormParams, "enum_form_string", r.enumFormString, "")
 	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
@@ -1608,13 +1619,13 @@ func (a *FakeApiService) TestGroupParametersExecute(r ApiTestGroupParametersRequ
 		return nil, reportError("requiredInt64Group is required and must be specified")
 	}
 
-	localVarQueryParams.Add("required_string_group", parameterToString(*r.requiredStringGroup, ""))
-	localVarQueryParams.Add("required_int64_group", parameterToString(*r.requiredInt64Group, ""))
+	parameterAddToQuery(localVarQueryParams, "required_string_group", r.requiredStringGroup, "")
+	parameterAddToQuery(localVarQueryParams, "required_int64_group", r.requiredInt64Group, "")
 	if r.stringGroup != nil {
-		localVarQueryParams.Add("string_group", parameterToString(*r.stringGroup, ""))
+	    parameterAddToQuery(localVarQueryParams, "string_group", r.stringGroup, "")
 	}
 	if r.int64Group != nil {
-		localVarQueryParams.Add("int64_group", parameterToString(*r.int64Group, ""))
+	    parameterAddToQuery(localVarQueryParams, "int64_group", r.int64Group, "")
 	}
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{}
@@ -1626,16 +1637,16 @@ func (a *FakeApiService) TestGroupParametersExecute(r ApiTestGroupParametersRequ
 	}
 
 	// to determine the Accept header
-	localVarHTTPHeaderAccepts := []string{"applicatino/json"}
+	localVarHTTPHeaderAccepts := []string{"application/json"}
 
 	// set Accept header
 	localVarHTTPHeaderAccept := selectHeaderAccept(localVarHTTPHeaderAccepts)
 	if localVarHTTPHeaderAccept != "" {
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
-	localVarHeaderParams["required_boolean_group"] = parameterToString(*r.requiredBooleanGroup, "")
+	parameterAddToQuery(localVarQueryParams, "required_boolean_group", r.requiredBooleanGroup, "")
 	if r.booleanGroup != nil {
-		localVarHeaderParams["boolean_group"] = parameterToString(*r.booleanGroup, "")
+		parameterAddToQuery(localVarQueryParams, "boolean_group", r.booleanGroup, "")
 	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
@@ -1855,8 +1866,112 @@ func (a *FakeApiService) TestJsonFormDataExecute(r ApiTestJsonFormDataRequest) (
 	if localVarHTTPHeaderAccept != "" {
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
-	localVarFormParams.Add("param", parameterToString(*r.param, ""))
-	localVarFormParams.Add("param2", parameterToString(*r.param2, ""))
+	parameterAddToQuery(localVarFormParams, "param", r.param, "")
+	parameterAddToQuery(localVarFormParams, "param2", r.param2, "")
+	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
+	if err != nil {
+		return nil, err
+	}
+
+	localVarHTTPResponse, err := a.client.callAPI(req)
+	if err != nil || localVarHTTPResponse == nil {
+		return localVarHTTPResponse, err
+	}
+
+	localVarBody, err := ioutil.ReadAll(localVarHTTPResponse.Body)
+	localVarHTTPResponse.Body.Close()
+	localVarHTTPResponse.Body = ioutil.NopCloser(bytes.NewBuffer(localVarBody))
+	if err != nil {
+		return localVarHTTPResponse, err
+	}
+
+	if localVarHTTPResponse.StatusCode >= 300 {
+		newErr := &GenericOpenAPIError{
+			body:  localVarBody,
+			error: localVarHTTPResponse.Status,
+		}
+		return localVarHTTPResponse, newErr
+	}
+
+	return localVarHTTPResponse, nil
+}
+
+type ApiTestQueryDeepObjectRequest struct {
+	ctx context.Context
+	ApiService FakeApi
+	testPet *Pet
+	inputOptions *Category
+}
+
+func (r ApiTestQueryDeepObjectRequest) TestPet(testPet Pet) ApiTestQueryDeepObjectRequest {
+	r.testPet = &testPet
+	return r
+}
+
+func (r ApiTestQueryDeepObjectRequest) InputOptions(inputOptions Category) ApiTestQueryDeepObjectRequest {
+	r.inputOptions = &inputOptions
+	return r
+}
+
+func (r ApiTestQueryDeepObjectRequest) Execute() (*http.Response, error) {
+	return r.ApiService.TestQueryDeepObjectExecute(r)
+}
+
+/*
+TestQueryDeepObject Method for TestQueryDeepObject
+
+ @param ctx context.Context - for authentication, logging, cancellation, deadlines, tracing, etc. Passed from http.Request or context.Background().
+ @return ApiTestQueryDeepObjectRequest
+*/
+func (a *FakeApiService) TestQueryDeepObject(ctx context.Context) ApiTestQueryDeepObjectRequest {
+	return ApiTestQueryDeepObjectRequest{
+		ApiService: a,
+		ctx: ctx,
+	}
+}
+
+// Execute executes the request
+func (a *FakeApiService) TestQueryDeepObjectExecute(r ApiTestQueryDeepObjectRequest) (*http.Response, error) {
+	var (
+		localVarHTTPMethod   = http.MethodGet
+		localVarPostBody     interface{}
+		formFiles            []formFile
+	)
+
+	localBasePath, err := a.client.cfg.ServerURLWithContext(r.ctx, "FakeApiService.TestQueryDeepObject")
+	if err != nil {
+		return nil, &GenericOpenAPIError{error: err.Error()}
+	}
+
+	localVarPath := localBasePath + "/fake/deep_object_test"
+
+	localVarHeaderParams := make(map[string]string)
+	localVarQueryParams := url.Values{}
+	localVarFormParams := url.Values{}
+
+	if r.testPet != nil {
+	    parameterAddToQuery(localVarQueryParams, "test_pet", r.testPet, "")
+	}
+	if r.inputOptions != nil {
+	    parameterAddToQuery(localVarQueryParams, "inputOptions", r.inputOptions, "")
+	}
+	// to determine the Content-Type header
+	localVarHTTPContentTypes := []string{}
+
+	// set Content-Type header
+	localVarHTTPContentType := selectHeaderContentType(localVarHTTPContentTypes)
+	if localVarHTTPContentType != "" {
+		localVarHeaderParams["Content-Type"] = localVarHTTPContentType
+	}
+
+	// to determine the Accept header
+	localVarHTTPHeaderAccepts := []string{}
+
+	// set Accept header
+	localVarHTTPHeaderAccept := selectHeaderAccept(localVarHTTPHeaderAccepts)
+	if localVarHTTPHeaderAccept != "" {
+		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
+	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
 		return nil, err
@@ -1978,24 +2093,24 @@ func (a *FakeApiService) TestQueryParameterCollectionFormatExecute(r ApiTestQuer
 		if reflect.TypeOf(t).Kind() == reflect.Slice {
 			s := reflect.ValueOf(t)
 			for i := 0; i < s.Len(); i++ {
-				localVarQueryParams.Add("pipe", parameterToString(s.Index(i), "multi"))
+				parameterAddToQuery(localVarQueryParams, "pipe", s.Index(i), "multi")
 			}
 		} else {
-			localVarQueryParams.Add("pipe", parameterToString(t, "multi"))
+			parameterAddToQuery(localVarQueryParams, "pipe", t, "multi")
 		}
 	}
-	localVarQueryParams.Add("ioutil", parameterToString(*r.ioutil, "csv"))
-	localVarQueryParams.Add("http", parameterToString(*r.http, "ssv"))
-	localVarQueryParams.Add("url", parameterToString(*r.url, "csv"))
+	parameterAddToQuery(localVarQueryParams, "ioutil", r.ioutil, "csv")
+	parameterAddToQuery(localVarQueryParams, "http", r.http, "ssv")
+	parameterAddToQuery(localVarQueryParams, "url", r.url, "csv")
 	{
 		t := *r.context
 		if reflect.TypeOf(t).Kind() == reflect.Slice {
 			s := reflect.ValueOf(t)
 			for i := 0; i < s.Len(); i++ {
-				localVarQueryParams.Add("context", parameterToString(s.Index(i), "multi"))
+				parameterAddToQuery(localVarQueryParams, "context", s.Index(i), "multi")
 			}
 		} else {
-			localVarQueryParams.Add("context", parameterToString(t, "multi"))
+			parameterAddToQuery(localVarQueryParams, "context", t, "multi")
 		}
 	}
 	// to determine the Content-Type header
@@ -2111,10 +2226,10 @@ func (a *FakeApiService) TestUniqueItemsHeaderAndQueryParameterCollectionFormatE
 		if reflect.TypeOf(t).Kind() == reflect.Slice {
 			s := reflect.ValueOf(t)
 			for i := 0; i < s.Len(); i++ {
-				localVarQueryParams.Add("queryUnique", parameterToString(s.Index(i), "multi"))
+				parameterAddToQuery(localVarQueryParams, "queryUnique", s.Index(i), "multi")
 			}
 		} else {
-			localVarQueryParams.Add("queryUnique", parameterToString(t, "multi"))
+			parameterAddToQuery(localVarQueryParams, "queryUnique", t, "multi")
 		}
 	}
 	// to determine the Content-Type header
@@ -2134,7 +2249,7 @@ func (a *FakeApiService) TestUniqueItemsHeaderAndQueryParameterCollectionFormatE
 	if localVarHTTPHeaderAccept != "" {
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
-	localVarHeaderParams["headerUnique"] = parameterToString(*r.headerUnique, "csv")
+	parameterAddToQuery(localVarQueryParams, "headerUnique", r.headerUnique, "csv")
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
 		return localVarReturnValue, nil, err

samples/openapi3/client/petstore/go/go-petstore/api_pet.go

@@ -304,7 +304,7 @@ func (a *PetApiService) DeletePetExecute(r ApiDeletePetRequest) (*http.Response,
 	}
 
 	localVarPath := localBasePath + "/pet/{petId}"
-	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterToString(r.petId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterValueToString(r.petId, "petId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -328,7 +328,7 @@ func (a *PetApiService) DeletePetExecute(r ApiDeletePetRequest) (*http.Response,
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.apiKey != nil {
-		localVarHeaderParams["api_key"] = parameterToString(*r.apiKey, "")
+		parameterAddToQuery(localVarQueryParams, "api_key", r.apiKey, "")
 	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
@@ -414,7 +414,7 @@ func (a *PetApiService) FindPetsByStatusExecute(r ApiFindPetsByStatusRequest) ([
 		return localVarReturnValue, nil, reportError("status is required and must be specified")
 	}
 
-	localVarQueryParams.Add("status", parameterToString(*r.status, "csv"))
+	parameterAddToQuery(localVarQueryParams, "status", r.status, "csv")
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{}
 
@@ -527,7 +527,7 @@ func (a *PetApiService) FindPetsByTagsExecute(r ApiFindPetsByTagsRequest) ([]Pet
 		return localVarReturnValue, nil, reportError("tags is required and must be specified")
 	}
 
-	localVarQueryParams.Add("tags", parameterToString(*r.tags, "csv"))
+	parameterAddToQuery(localVarQueryParams, "tags", r.tags, "csv")
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{}
 
@@ -625,7 +625,7 @@ func (a *PetApiService) GetPetByIdExecute(r ApiGetPetByIdRequest) (*Pet, *http.R
 	}
 
 	localVarPath := localBasePath + "/pet/{petId}"
-	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterToString(r.petId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterValueToString(r.petId, "petId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -854,7 +854,7 @@ func (a *PetApiService) UpdatePetWithFormExecute(r ApiUpdatePetWithFormRequest)
 	}
 
 	localVarPath := localBasePath + "/pet/{petId}"
-	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterToString(r.petId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterValueToString(r.petId, "petId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -878,10 +878,10 @@ func (a *PetApiService) UpdatePetWithFormExecute(r ApiUpdatePetWithFormRequest)
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.name != nil {
-		localVarFormParams.Add("name", parameterToString(*r.name, ""))
+		parameterAddToQuery(localVarFormParams, "name", r.name, "")
 	}
 	if r.status != nil {
-		localVarFormParams.Add("status", parameterToString(*r.status, ""))
+		parameterAddToQuery(localVarFormParams, "status", r.status, "")
 	}
 	req, err := a.client.prepareRequest(r.ctx, localVarPath, localVarHTTPMethod, localVarPostBody, localVarHeaderParams, localVarQueryParams, localVarFormParams, formFiles)
 	if err != nil {
@@ -968,7 +968,7 @@ func (a *PetApiService) UploadFileExecute(r ApiUploadFileRequest) (*ApiResponse,
 	}
 
 	localVarPath := localBasePath + "/pet/{petId}/uploadImage"
-	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterToString(r.petId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterValueToString(r.petId, "petId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -992,7 +992,7 @@ func (a *PetApiService) UploadFileExecute(r ApiUploadFileRequest) (*ApiResponse,
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.additionalMetadata != nil {
-		localVarFormParams.Add("additionalMetadata", parameterToString(*r.additionalMetadata, ""))
+		parameterAddToQuery(localVarFormParams, "additionalMetadata", r.additionalMetadata, "")
 	}
 	var fileLocalVarFormFileName string
 	var fileLocalVarFileName     string
@@ -1105,7 +1105,7 @@ func (a *PetApiService) UploadFileWithRequiredFileExecute(r ApiUploadFileWithReq
 	}
 
 	localVarPath := localBasePath + "/fake/{petId}/uploadImageWithRequiredFile"
-	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterToString(r.petId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"petId"+"}", url.PathEscape(parameterValueToString(r.petId, "petId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -1132,7 +1132,7 @@ func (a *PetApiService) UploadFileWithRequiredFileExecute(r ApiUploadFileWithReq
 		localVarHeaderParams["Accept"] = localVarHTTPHeaderAccept
 	}
 	if r.additionalMetadata != nil {
-		localVarFormParams.Add("additionalMetadata", parameterToString(*r.additionalMetadata, ""))
+		parameterAddToQuery(localVarFormParams, "additionalMetadata", r.additionalMetadata, "")
 	}
 	var requiredFileLocalVarFormFileName string
 	var requiredFileLocalVarFileName     string

samples/openapi3/client/petstore/go/go-petstore/api_store.go

@@ -124,7 +124,7 @@ func (a *StoreApiService) DeleteOrderExecute(r ApiDeleteOrderRequest) (*http.Res
 	}
 
 	localVarPath := localBasePath + "/store/order/{order_id}"
-	localVarPath = strings.Replace(localVarPath, "{"+"order_id"+"}", url.PathEscape(parameterToString(r.orderId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"order_id"+"}", url.PathEscape(parameterValueToString(r.orderId, "orderId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -331,7 +331,7 @@ func (a *StoreApiService) GetOrderByIdExecute(r ApiGetOrderByIdRequest) (*Order,
 	}
 
 	localVarPath := localBasePath + "/store/order/{order_id}"
-	localVarPath = strings.Replace(localVarPath, "{"+"order_id"+"}", url.PathEscape(parameterToString(r.orderId, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"order_id"+"}", url.PathEscape(parameterValueToString(r.orderId, "orderId")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}

samples/openapi3/client/petstore/go/go-petstore/api_user.go

@@ -476,7 +476,7 @@ func (a *UserApiService) DeleteUserExecute(r ApiDeleteUserRequest) (*http.Respon
 	}
 
 	localVarPath := localBasePath + "/user/{username}"
-	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterToString(r.username, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterValueToString(r.username, "username")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -570,7 +570,7 @@ func (a *UserApiService) GetUserByNameExecute(r ApiGetUserByNameRequest) (*User,
 	}
 
 	localVarPath := localBasePath + "/user/{username}"
-	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterToString(r.username, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterValueToString(r.username, "username")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}
@@ -695,8 +695,8 @@ func (a *UserApiService) LoginUserExecute(r ApiLoginUserRequest) (string, *http.
 		return localVarReturnValue, nil, reportError("password is required and must be specified")
 	}
 
-	localVarQueryParams.Add("username", parameterToString(*r.username, ""))
-	localVarQueryParams.Add("password", parameterToString(*r.password, ""))
+	parameterAddToQuery(localVarQueryParams, "username", r.username, "")
+	parameterAddToQuery(localVarQueryParams, "password", r.password, "")
 	// to determine the Content-Type header
 	localVarHTTPContentTypes := []string{}
 
@@ -887,7 +887,7 @@ func (a *UserApiService) UpdateUserExecute(r ApiUpdateUserRequest) (*http.Respon
 	}
 
 	localVarPath := localBasePath + "/user/{username}"
-	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterToString(r.username, "")), -1)
+	localVarPath = strings.Replace(localVarPath, "{"+"username"+"}", url.PathEscape(parameterValueToString(r.username, "username")), -1)
 
 	localVarHeaderParams := make(map[string]string)
 	localVarQueryParams := url.Values{}

samples/openapi3/client/petstore/go/go-petstore/client.go

@@ -39,6 +39,8 @@ import (
 var (
 	jsonCheck = regexp.MustCompile(`(?i:(?:application|text)/(?:vnd\.[^;]+\+)?json)`)
 	xmlCheck  = regexp.MustCompile(`(?i:(?:application|text)/xml)`)
+    queryParamSplit = regexp.MustCompile(`(^|&)([^&]+)`)
+    queryDescape    = strings.NewReplacer( "%5B", "[", "%5D", "]" )
 )
 
 // APIClient manages communication with the OpenAPI Petstore API v1.0.0
@@ -143,29 +145,102 @@ func typeCheckParameter(obj interface{}, expected string, name string) error {
 	return nil
 }
 
-// parameterToString convert interface{} parameters to string, using a delimiter if format is provided.
-func parameterToString(obj interface{}, collectionFormat string) string {
-	var delimiter string
-
-	switch collectionFormat {
-	case "pipes":
-		delimiter = "|"
-	case "ssv":
-		delimiter = " "
-	case "tsv":
-		delimiter = "\t"
-	case "csv":
-		delimiter = ","
-	}
-
-	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)
-	}
-
+func parameterValueToString( obj interface{}, key string ) string {
+    if reflect.TypeOf(obj).Kind() != reflect.Ptr {
         return fmt.Sprintf("%v", obj)
     }
+    var param,ok = obj.(MappedNullable)
+    if !ok {
+        return ""
+    }
+    dataMap,err := param.ToMap()
+    if err != nil {
+        return ""
+    }
+    return fmt.Sprintf("%v", dataMap[key])
+}
+
+// parameterAddToQuery adds the provided object to the url query supporting deep object syntax
+func parameterAddToQuery(queryParams interface{}, keyPrefix string, obj interface{}, collectionType string) {
+    var v = reflect.ValueOf(obj)
+    var value = ""
+    if v == reflect.ValueOf(nil) {
+        value = "null"
+    } else {
+        switch v.Kind() {
+			case reflect.Invalid:
+				value = "invalid"
+
+			case reflect.Struct:
+				if t,ok := obj.(MappedNullable); ok {
+					dataMap,err := t.ToMap()
+					if err != nil {
+						return
+					}
+					parameterAddToQuery(queryParams, keyPrefix, dataMap, collectionType)
+					return
+				}
+				if t, ok := obj.(time.Time); ok {
+					parameterAddToQuery(queryParams, keyPrefix, t.Format(time.RFC3339), collectionType)
+					return
+				}
+				value = v.Type().String() + " value"
+			case reflect.Slice:
+				var indValue = reflect.ValueOf(obj)
+				if indValue == reflect.ValueOf(nil) {
+					return
+				}
+				var lenIndValue = indValue.Len()
+				for i:=0;i<lenIndValue;i++ {
+					var arrayValue = indValue.Index(i)
+					parameterAddToQuery(queryParams, keyPrefix, arrayValue.Interface(), collectionType)
+				}
+				return
+
+			case reflect.Map:
+				var indValue = reflect.ValueOf(obj)
+				if indValue == reflect.ValueOf(nil) {
+					return
+				}
+				iter := indValue.MapRange()
+				for iter.Next() {
+					k,v := iter.Key(), iter.Value()
+					parameterAddToQuery(queryParams, fmt.Sprintf("%s[%s]", keyPrefix, k.String()), v.Interface(), collectionType)
+				}
+				return
+
+			case reflect.Interface:
+				fallthrough
+            case reflect.Ptr:
+				parameterAddToQuery(queryParams, keyPrefix, v.Elem().Interface(), collectionType)
+                return
+
+            case reflect.Int, reflect.Int8, reflect.Int16,
+                reflect.Int32, reflect.Int64:
+                value = strconv.FormatInt(v.Int(), 10)
+            case reflect.Uint, reflect.Uint8, reflect.Uint16,
+                reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+                value = strconv.FormatUint(v.Uint(), 10)
+            case reflect.Float32, reflect.Float64:
+                value = strconv.FormatFloat(v.Float(), 'g', -1, 32)
+            case reflect.Bool:
+                value = strconv.FormatBool(v.Bool())
+            case reflect.String:
+                value = v.String()
+            default:
+                value = v.Type().String() + " value"
+        }
+    }
+
+    switch valuesMap := queryParams.(type) {
+        case url.Values:
+            valuesMap.Add( keyPrefix, value )
+            break
+        case map[string]string:
+            valuesMap[keyPrefix] = value
+            break
+    }
+}
 
 // helper for converting interface{} parameters to json strings
 func parameterToJson(obj interface{}) (string, error) {
@@ -316,7 +391,11 @@ func (c *APIClient) prepareRequest(
 	}
 
 	// Encode the parameters.
-	url.RawQuery = query.Encode()
+    url.RawQuery = queryParamSplit.ReplaceAllStringFunc(query.Encode(), func(s string) string {
+        pieces := strings.Split(s, "=")
+        pieces[0] = queryDescape.Replace(pieces[0])
+        return strings.Join(pieces, "=")
+    })
 
 	// Generate a new request
 	if body != nil {

samples/openapi3/client/petstore/go/go-petstore/docs/FakeApi.md

@@ -17,6 +17,7 @@ Method | HTTP request | Description
 [**TestGroupParameters**](FakeApi.md#TestGroupParameters) | **Delete** /fake | Fake endpoint to test group parameters (optional)
 [**TestInlineAdditionalProperties**](FakeApi.md#TestInlineAdditionalProperties) | **Post** /fake/inline-additionalProperties | test inline additionalProperties
 [**TestJsonFormData**](FakeApi.md#TestJsonFormData) | **Get** /fake/jsonFormData | test json serialization of form data
+[**TestQueryDeepObject**](FakeApi.md#TestQueryDeepObject) | **Get** /fake/deep_object_test | 
 [**TestQueryParameterCollectionFormat**](FakeApi.md#TestQueryParameterCollectionFormat) | **Put** /fake/test-query-parameters | 
 [**TestUniqueItemsHeaderAndQueryParameterCollectionFormat**](FakeApi.md#TestUniqueItemsHeaderAndQueryParameterCollectionFormat) | **Put** /fake/test-unique-parameters | 
 
@@ -775,7 +776,7 @@ Name | Type | Description  | Notes
 ### HTTP request headers
 
 - **Content-Type**: Not defined
-- **Accept**: applicatino/json
+- **Accept**: application/json
 
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints)
 [[Back to Model list]](../README.md#documentation-for-models)
@@ -912,6 +913,70 @@ No authorization required
 [[Back to README]](../README.md)
 
 
+## TestQueryDeepObject
+
+> TestQueryDeepObject(ctx).TestPet(testPet).InputOptions(inputOptions).Execute()
+
+
+
+### Example
+
+```go
+package main
+
+import (
+    "context"
+    "fmt"
+    "os"
+    openapiclient "./openapi"
+)
+
+func main() {
+    testPet := map[string][]openapiclient.Pet{"key": map[string]interface{}{ ... }} // Pet |  (optional)
+    inputOptions := map[string][]openapiclient.Category{"key": map[string]interface{}{ ... }} // Category |  (optional)
+
+    configuration := openapiclient.NewConfiguration()
+    apiClient := openapiclient.NewAPIClient(configuration)
+    resp, r, err := apiClient.FakeApi.TestQueryDeepObject(context.Background()).TestPet(testPet).InputOptions(inputOptions).Execute()
+    if err != nil {
+        fmt.Fprintf(os.Stderr, "Error when calling `FakeApi.TestQueryDeepObject``: %v\n", err)
+        fmt.Fprintf(os.Stderr, "Full HTTP response: %v\n", r)
+    }
+}
+```
+
+### Path Parameters
+
+
+
+### Other Parameters
+
+Other parameters are passed through a pointer to a apiTestQueryDeepObjectRequest struct via the builder pattern
+
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **testPet** | [**Pet**](Pet.md) |  | 
+ **inputOptions** | [**Category**](Category.md) |  | 
+
+### Return type
+
+ (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+- **Content-Type**: Not defined
+- **Accept**: Not defined
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints)
+[[Back to Model list]](../README.md#documentation-for-models)
+[[Back to README]](../README.md)
+
+
 ## TestQueryParameterCollectionFormat
 
 > TestQueryParameterCollectionFormat(ctx).Pipe(pipe).Ioutil(ioutil).Http(http).Url(url).Context(context).Execute()

samples/openapi3/client/petstore/go/go-petstore/model_200_response.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Model200Response type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Model200Response{}
+
 // Model200Response Model for testing model name starting with number
 type Model200Response struct {
 	Name *int32 `json:"name,omitempty"`
@@ -105,6 +108,14 @@ func (o *Model200Response) SetClass(v string) {
 }
 
 func (o Model200Response) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Model200Response) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Name) {
 		toSerialize["name"] = o.Name
@@ -117,7 +128,7 @@ func (o Model200Response) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *Model200Response) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model__foo_get_default_response.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the FooGetDefaultResponse type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &FooGetDefaultResponse{}
+
 // FooGetDefaultResponse struct for FooGetDefaultResponse
 type FooGetDefaultResponse struct {
 	String *Foo `json:"string,omitempty"`
@@ -72,6 +75,14 @@ func (o *FooGetDefaultResponse) SetString(v Foo) {
 }
 
 func (o FooGetDefaultResponse) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o FooGetDefaultResponse) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.String) {
 		toSerialize["string"] = o.String
@@ -81,7 +92,7 @@ func (o FooGetDefaultResponse) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *FooGetDefaultResponse) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model__special_model_name_.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the SpecialModelName type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &SpecialModelName{}
+
 // SpecialModelName struct for SpecialModelName
 type SpecialModelName struct {
 	SpecialPropertyName *int64 `json:"$special[property.name],omitempty"`
@@ -72,6 +75,14 @@ func (o *SpecialModelName) SetSpecialPropertyName(v int64) {
 }
 
 func (o SpecialModelName) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o SpecialModelName) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.SpecialPropertyName) {
 		toSerialize["$special[property.name]"] = o.SpecialPropertyName
@@ -81,7 +92,7 @@ func (o SpecialModelName) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *SpecialModelName) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_additional_properties_class.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the AdditionalPropertiesClass type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &AdditionalPropertiesClass{}
+
 // AdditionalPropertiesClass struct for AdditionalPropertiesClass
 type AdditionalPropertiesClass struct {
 	MapProperty *map[string]string `json:"map_property,omitempty"`
@@ -105,6 +108,14 @@ func (o *AdditionalPropertiesClass) SetMapOfMapProperty(v map[string]map[string]
 }
 
 func (o AdditionalPropertiesClass) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o AdditionalPropertiesClass) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.MapProperty) {
 		toSerialize["map_property"] = o.MapProperty
@@ -117,7 +128,7 @@ func (o AdditionalPropertiesClass) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *AdditionalPropertiesClass) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_animal.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Animal type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Animal{}
+
 // Animal struct for Animal
 type Animal struct {
 	ClassName string `json:"className"`
@@ -102,10 +105,16 @@ func (o *Animal) SetColor(v string) {
 }
 
 func (o Animal) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if true {
-		toSerialize["className"] = o.ClassName
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
 	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Animal) ToMap() (map[string]interface{}, error) {
+	toSerialize := map[string]interface{}{}
+	toSerialize["className"] = o.ClassName
 	if !isNil(o.Color) {
 		toSerialize["color"] = o.Color
 	}
@@ -114,7 +123,7 @@ func (o Animal) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *Animal) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_api_response.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ApiResponse type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ApiResponse{}
+
 // ApiResponse struct for ApiResponse
 type ApiResponse struct {
 	Code *int32 `json:"code,omitempty"`
@@ -138,6 +141,14 @@ func (o *ApiResponse) SetMessage(v string) {
 }
 
 func (o ApiResponse) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ApiResponse) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Code) {
 		toSerialize["code"] = o.Code
@@ -153,7 +164,7 @@ func (o ApiResponse) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *ApiResponse) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_apple.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Apple type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Apple{}
+
 // Apple struct for Apple
 type Apple struct {
 	Cultivar *string `json:"cultivar,omitempty"`
@@ -72,6 +75,14 @@ func (o *Apple) SetCultivar(v string) {
 }
 
 func (o Apple) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Apple) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Cultivar) {
 		toSerialize["cultivar"] = o.Cultivar
@@ -81,7 +92,7 @@ func (o Apple) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *Apple) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_apple_req.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the AppleReq type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &AppleReq{}
+
 // AppleReq struct for AppleReq
 type AppleReq struct {
 	Cultivar string `json:"cultivar"`
@@ -98,10 +101,16 @@ func (o *AppleReq) SetMealy(v bool) {
 }
 
 func (o AppleReq) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if true {
-		toSerialize["cultivar"] = o.Cultivar
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
 	}
+	return json.Marshal(toSerialize)
+}
+
+func (o AppleReq) ToMap() (map[string]interface{}, error) {
+	toSerialize := map[string]interface{}{}
+	toSerialize["cultivar"] = o.Cultivar
 	if !isNil(o.Mealy) {
 		toSerialize["mealy"] = o.Mealy
 	}
@@ -110,7 +119,7 @@ func (o AppleReq) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *AppleReq) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_array_of_array_of_number_only.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ArrayOfArrayOfNumberOnly type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ArrayOfArrayOfNumberOnly{}
+
 // ArrayOfArrayOfNumberOnly struct for ArrayOfArrayOfNumberOnly
 type ArrayOfArrayOfNumberOnly struct {
 	ArrayArrayNumber [][]float32 `json:"ArrayArrayNumber,omitempty"`
@@ -72,6 +75,14 @@ func (o *ArrayOfArrayOfNumberOnly) SetArrayArrayNumber(v [][]float32) {
 }
 
 func (o ArrayOfArrayOfNumberOnly) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ArrayOfArrayOfNumberOnly) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.ArrayArrayNumber) {
 		toSerialize["ArrayArrayNumber"] = o.ArrayArrayNumber
@@ -81,7 +92,7 @@ func (o ArrayOfArrayOfNumberOnly) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *ArrayOfArrayOfNumberOnly) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_array_of_number_only.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ArrayOfNumberOnly type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ArrayOfNumberOnly{}
+
 // ArrayOfNumberOnly struct for ArrayOfNumberOnly
 type ArrayOfNumberOnly struct {
 	ArrayNumber []float32 `json:"ArrayNumber,omitempty"`
@@ -72,6 +75,14 @@ func (o *ArrayOfNumberOnly) SetArrayNumber(v []float32) {
 }
 
 func (o ArrayOfNumberOnly) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ArrayOfNumberOnly) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.ArrayNumber) {
 		toSerialize["ArrayNumber"] = o.ArrayNumber
@@ -81,7 +92,7 @@ func (o ArrayOfNumberOnly) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *ArrayOfNumberOnly) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_array_test_.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ArrayTest type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ArrayTest{}
+
 // ArrayTest struct for ArrayTest
 type ArrayTest struct {
 	ArrayOfString []string `json:"array_of_string,omitempty"`
@@ -138,6 +141,14 @@ func (o *ArrayTest) SetArrayArrayOfModel(v [][]ReadOnlyFirst) {
 }
 
 func (o ArrayTest) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ArrayTest) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.ArrayOfString) {
 		toSerialize["array_of_string"] = o.ArrayOfString
@@ -153,7 +164,7 @@ func (o ArrayTest) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *ArrayTest) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_banana.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Banana type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Banana{}
+
 // Banana struct for Banana
 type Banana struct {
 	LengthCm *float32 `json:"lengthCm,omitempty"`
@@ -72,6 +75,14 @@ func (o *Banana) SetLengthCm(v float32) {
 }
 
 func (o Banana) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Banana) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.LengthCm) {
 		toSerialize["lengthCm"] = o.LengthCm
@@ -81,7 +92,7 @@ func (o Banana) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *Banana) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_banana_req.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the BananaReq type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &BananaReq{}
+
 // BananaReq struct for BananaReq
 type BananaReq struct {
 	LengthCm float32 `json:"lengthCm"`
@@ -98,10 +101,16 @@ func (o *BananaReq) SetSweet(v bool) {
 }
 
 func (o BananaReq) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if true {
-		toSerialize["lengthCm"] = o.LengthCm
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
 	}
+	return json.Marshal(toSerialize)
+}
+
+func (o BananaReq) ToMap() (map[string]interface{}, error) {
+	toSerialize := map[string]interface{}{}
+	toSerialize["lengthCm"] = o.LengthCm
 	if !isNil(o.Sweet) {
 		toSerialize["sweet"] = o.Sweet
 	}
@@ -110,7 +119,7 @@ func (o BananaReq) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *BananaReq) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_capitalization.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Capitalization type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Capitalization{}
+
 // Capitalization struct for Capitalization
 type Capitalization struct {
 	SmallCamel *string `json:"smallCamel,omitempty"`
@@ -238,6 +241,14 @@ func (o *Capitalization) SetATT_NAME(v string) {
 }
 
 func (o Capitalization) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Capitalization) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.SmallCamel) {
 		toSerialize["smallCamel"] = o.SmallCamel
@@ -262,7 +273,7 @@ func (o Capitalization) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *Capitalization) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_cat.go

@@ -16,6 +16,9 @@ import (
 	"strings"
 )
 
+// checks if the Cat type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Cat{}
+
 // Cat struct for Cat
 type Cat struct {
 	Animal
@@ -78,14 +81,22 @@ func (o *Cat) SetDeclawed(v bool) {
 }
 
 func (o Cat) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Cat) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	serializedAnimal, errAnimal := json.Marshal(o.Animal)
 	if errAnimal != nil {
-		return []byte{}, errAnimal
+		return map[string]interface{}{}, errAnimal
 	}
 	errAnimal = json.Unmarshal([]byte(serializedAnimal), &toSerialize)
 	if errAnimal != nil {
-		return []byte{}, errAnimal
+		return map[string]interface{}{}, errAnimal
 	}
 	if !isNil(o.Declawed) {
 		toSerialize["declawed"] = o.Declawed
@@ -95,7 +106,7 @@ func (o Cat) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *Cat) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_cat_all_of.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the CatAllOf type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &CatAllOf{}
+
 // CatAllOf struct for CatAllOf
 type CatAllOf struct {
 	Declawed *bool `json:"declawed,omitempty"`
@@ -72,6 +75,14 @@ func (o *CatAllOf) SetDeclawed(v bool) {
 }
 
 func (o CatAllOf) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o CatAllOf) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Declawed) {
 		toSerialize["declawed"] = o.Declawed
@@ -81,7 +92,7 @@ func (o CatAllOf) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *CatAllOf) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_category.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Category type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Category{}
+
 // Category struct for Category
 type Category struct {
 	Id *int64 `json:"id,omitempty"`
@@ -100,19 +103,25 @@ func (o *Category) SetName(v string) {
 }
 
 func (o Category) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Category) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Id) {
 		toSerialize["id"] = o.Id
 	}
-	if true {
 	toSerialize["name"] = o.Name
-	}
 
 	for key, value := range o.AdditionalProperties {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *Category) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_class_model.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the ClassModel type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &ClassModel{}
+
 // ClassModel Model for testing model with \"_class\" property
 type ClassModel struct {
 	Class *string `json:"_class,omitempty"`
@@ -72,6 +75,14 @@ func (o *ClassModel) SetClass(v string) {
 }
 
 func (o ClassModel) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o ClassModel) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Class) {
 		toSerialize["_class"] = o.Class
@@ -81,7 +92,7 @@ func (o ClassModel) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *ClassModel) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_client.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Client type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Client{}
+
 // Client struct for Client
 type Client struct {
 	Client *string `json:"client,omitempty"`
@@ -72,6 +75,14 @@ func (o *Client) SetClient(v string) {
 }
 
 func (o Client) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Client) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Client) {
 		toSerialize["client"] = o.Client
@@ -81,7 +92,7 @@ func (o Client) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *Client) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_dog.go

@@ -16,6 +16,9 @@ import (
 	"strings"
 )
 
+// checks if the Dog type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Dog{}
+
 // Dog struct for Dog
 type Dog struct {
 	Animal
@@ -78,14 +81,22 @@ func (o *Dog) SetBreed(v string) {
 }
 
 func (o Dog) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Dog) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	serializedAnimal, errAnimal := json.Marshal(o.Animal)
 	if errAnimal != nil {
-		return []byte{}, errAnimal
+		return map[string]interface{}{}, errAnimal
 	}
 	errAnimal = json.Unmarshal([]byte(serializedAnimal), &toSerialize)
 	if errAnimal != nil {
-		return []byte{}, errAnimal
+		return map[string]interface{}{}, errAnimal
 	}
 	if !isNil(o.Breed) {
 		toSerialize["breed"] = o.Breed
@@ -95,7 +106,7 @@ func (o Dog) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *Dog) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_dog_all_of.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the DogAllOf type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &DogAllOf{}
+
 // DogAllOf struct for DogAllOf
 type DogAllOf struct {
 	Breed *string `json:"breed,omitempty"`
@@ -72,6 +75,14 @@ func (o *DogAllOf) SetBreed(v string) {
 }
 
 func (o DogAllOf) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o DogAllOf) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Breed) {
 		toSerialize["breed"] = o.Breed
@@ -81,7 +92,7 @@ func (o DogAllOf) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *DogAllOf) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_duplicated_prop_child.go

@@ -16,6 +16,9 @@ import (
 	"strings"
 )
 
+// checks if the DuplicatedPropChild type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &DuplicatedPropChild{}
+
 // DuplicatedPropChild struct for DuplicatedPropChild
 type DuplicatedPropChild struct {
 	DuplicatedPropParent
@@ -76,14 +79,22 @@ func (o *DuplicatedPropChild) SetDupProp(v string) {
 }
 
 func (o DuplicatedPropChild) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o DuplicatedPropChild) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	serializedDuplicatedPropParent, errDuplicatedPropParent := json.Marshal(o.DuplicatedPropParent)
 	if errDuplicatedPropParent != nil {
-		return []byte{}, errDuplicatedPropParent
+		return map[string]interface{}{}, errDuplicatedPropParent
 	}
 	errDuplicatedPropParent = json.Unmarshal([]byte(serializedDuplicatedPropParent), &toSerialize)
 	if errDuplicatedPropParent != nil {
-		return []byte{}, errDuplicatedPropParent
+		return map[string]interface{}{}, errDuplicatedPropParent
 	}
 	if !isNil(o.DupProp) {
 		toSerialize["dup-prop"] = o.DupProp
@@ -93,7 +104,7 @@ func (o DuplicatedPropChild) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *DuplicatedPropChild) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_duplicated_prop_child_all_of.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the DuplicatedPropChildAllOf type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &DuplicatedPropChildAllOf{}
+
 // DuplicatedPropChildAllOf struct for DuplicatedPropChildAllOf
 type DuplicatedPropChildAllOf struct {
 	// A discriminator value
@@ -73,6 +76,14 @@ func (o *DuplicatedPropChildAllOf) SetDupProp(v string) {
 }
 
 func (o DuplicatedPropChildAllOf) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o DuplicatedPropChildAllOf) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.DupProp) {
 		toSerialize["dup-prop"] = o.DupProp
@@ -82,7 +93,7 @@ func (o DuplicatedPropChildAllOf) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *DuplicatedPropChildAllOf) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_duplicated_prop_parent.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the DuplicatedPropParent type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &DuplicatedPropParent{}
+
 // DuplicatedPropParent parent model with duplicated property
 type DuplicatedPropParent struct {
 	// A discriminator value
@@ -66,16 +69,22 @@ func (o *DuplicatedPropParent) SetDupProp(v string) {
 }
 
 func (o DuplicatedPropParent) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if true {
-		toSerialize["dup-prop"] = o.DupProp
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
 	}
+	return json.Marshal(toSerialize)
+}
+
+func (o DuplicatedPropParent) ToMap() (map[string]interface{}, error) {
+	toSerialize := map[string]interface{}{}
+	toSerialize["dup-prop"] = o.DupProp
 
 	for key, value := range o.AdditionalProperties {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *DuplicatedPropParent) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_enum_arrays.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the EnumArrays type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &EnumArrays{}
+
 // EnumArrays struct for EnumArrays
 type EnumArrays struct {
 	JustSymbol *string `json:"just_symbol,omitempty"`
@@ -105,6 +108,14 @@ func (o *EnumArrays) SetArrayEnum(v []string) {
 }
 
 func (o EnumArrays) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o EnumArrays) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.JustSymbol) {
 		toSerialize["just_symbol"] = o.JustSymbol
@@ -117,7 +128,7 @@ func (o EnumArrays) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *EnumArrays) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_enum_test_.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the EnumTest type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &EnumTest{}
+
 // EnumTest struct for EnumTest
 type EnumTest struct {
 	EnumString *string `json:"enum_string,omitempty"`
@@ -314,13 +317,19 @@ func (o *EnumTest) SetOuterEnumIntegerDefaultValue(v OuterEnumIntegerDefaultValu
 }
 
 func (o EnumTest) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o EnumTest) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.EnumString) {
 		toSerialize["enum_string"] = o.EnumString
 	}
-	if true {
 	toSerialize["enum_string_required"] = o.EnumStringRequired
-	}
 	if !isNil(o.EnumInteger) {
 		toSerialize["enum_integer"] = o.EnumInteger
 	}
@@ -344,7 +353,7 @@ func (o EnumTest) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *EnumTest) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_file.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the File type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &File{}
+
 // File Must be named `File` for test.
 type File struct {
 	// Test capitalization
@@ -73,6 +76,14 @@ func (o *File) SetSourceURI(v string) {
 }
 
 func (o File) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o File) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.SourceURI) {
 		toSerialize["sourceURI"] = o.SourceURI
@@ -82,7 +93,7 @@ func (o File) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *File) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_file_schema_test_class.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the FileSchemaTestClass type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &FileSchemaTestClass{}
+
 // FileSchemaTestClass struct for FileSchemaTestClass
 type FileSchemaTestClass struct {
 	File *File `json:"file,omitempty"`
@@ -105,6 +108,14 @@ func (o *FileSchemaTestClass) SetFiles(v []File) {
 }
 
 func (o FileSchemaTestClass) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o FileSchemaTestClass) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.File) {
 		toSerialize["file"] = o.File
@@ -117,7 +128,7 @@ func (o FileSchemaTestClass) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *FileSchemaTestClass) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_foo.go

@@ -14,6 +14,9 @@ import (
 	"encoding/json"
 )
 
+// checks if the Foo type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &Foo{}
+
 // Foo struct for Foo
 type Foo struct {
 	Bar *string `json:"bar,omitempty"`
@@ -76,6 +79,14 @@ func (o *Foo) SetBar(v string) {
 }
 
 func (o Foo) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o Foo) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Bar) {
 		toSerialize["bar"] = o.Bar
@@ -85,7 +96,7 @@ func (o Foo) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *Foo) UnmarshalJSON(bytes []byte) (err error) {

samples/openapi3/client/petstore/go/go-petstore/model_format_test_.go

@@ -16,6 +16,9 @@ import (
 	"time"
 )
 
+// checks if the FormatTest type satisfies the MappedNullable interface at compile time
+var _ MappedNullable = &FormatTest{}
+
 // FormatTest struct for FormatTest
 type FormatTest struct {
 	Integer *int32 `json:"integer,omitempty"`
@@ -510,6 +513,14 @@ func (o *FormatTest) SetPatternWithDigitsAndDelimiter(v string) {
 }
 
 func (o FormatTest) MarshalJSON() ([]byte, error) {
+	toSerialize,err := o.ToMap()
+	if err != nil {
+		return []byte{}, err
+	}
+	return json.Marshal(toSerialize)
+}
+
+func (o FormatTest) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
 	if !isNil(o.Integer) {
 		toSerialize["integer"] = o.Integer
@@ -520,9 +531,7 @@ func (o FormatTest) MarshalJSON() ([]byte, error) {
 	if !isNil(o.Int64) {
 		toSerialize["int64"] = o.Int64
 	}
-	if true {
 	toSerialize["number"] = o.Number
-	}
 	if !isNil(o.Float) {
 		toSerialize["float"] = o.Float
 	}
@@ -532,24 +541,18 @@ func (o FormatTest) MarshalJSON() ([]byte, error) {
 	if !isNil(o.String) {
 		toSerialize["string"] = o.String
 	}
-	if true {
 	toSerialize["byte"] = o.Byte
-	}
 	if !isNil(o.Binary) {
 		toSerialize["binary"] = o.Binary
 	}
-	if true {
 	toSerialize["date"] = o.Date
-	}
 	if !isNil(o.DateTime) {
 		toSerialize["dateTime"] = o.DateTime
 	}
 	if !isNil(o.Uuid) {
 		toSerialize["uuid"] = o.Uuid
 	}
-	if true {
 	toSerialize["password"] = o.Password
-	}
 	if !isNil(o.PatternWithDigits) {
 		toSerialize["pattern_with_digits"] = o.PatternWithDigits
 	}
@@ -561,7 +564,7 @@ func (o FormatTest) MarshalJSON() ([]byte, error) {
 		toSerialize[key] = value
 	}
 
-	return json.Marshal(toSerialize)
+	return toSerialize, nil
 }
 
 func (o *FormatTest) UnmarshalJSON(bytes []byte) (err error) {