diff --git a/modules/swagger-codegen/src/main/resources/typescript-angular/api.service.mustache b/modules/swagger-codegen/src/main/resources/typescript-angular/api.service.mustache
index 1dd20307db1..47a46651b8b 100644
--- a/modules/swagger-codegen/src/main/resources/typescript-angular/api.service.mustache
+++ b/modules/swagger-codegen/src/main/resources/typescript-angular/api.service.mustache
@@ -34,6 +34,25 @@ import { Configuration }                                     from '../configurat
 import { {{classname}}Interface }                            from './{{classFilename}}Interface';
 {{/withInterfaces}}
 
+{{#useHttpClient}}
+    import { HttpClient, HttpHeaders, HttpParams,
+    HttpResponse, HttpEvent }                           from '@angular/common/http';
+    import { CustomHttpUrlEncodingCodec }                        from '../encoder';
+{{/useHttpClient}}
+{{^useHttpClient}}
+    import { Http, Headers, URLSearchParams }                    from '@angular/http';
+    import { RequestMethod, RequestOptions, RequestOptionsArgs } from '@angular/http';
+    import { Response, ResponseContentType }                     from '@angular/http';
+    import { CustomQueryEncoderHelper }                          from '../encoder';
+{{/useHttpClient}}
+
+
+type FormParams = URLSearchParams | FormData{{#useHttpClient}} | HttpParams{{/useHttpClient}};
+
+function append(formParams: FormParams, param: string, value: any) {
+    return {{#useHttpClient}}formParams.append(param, value){{/useHttpClient}}{{^useHttpClient}}formParams.append(param, value), formParams{{/useHttpClient}}
+};
+
 {{#operations}}
 
 {{#description}}
@@ -262,7 +281,7 @@ export class {{classname}} {
 {{#hasFormParams}}
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
         let useForm = false;
         let convertFormParamsToString = false;
 {{#formParams}}
@@ -286,23 +305,22 @@ export class {{classname}} {
             headers.set('Content-Type', 'application/x-www-form-urlencoded;charset=UTF-8');
 {{/useHttpClient}}
         }
-
 {{#formParams}}
         {{#isListContainer}}
         if ({{paramName}}) {
         {{#isCollectionFormatMulti}}
             {{paramName}}.forEach((element) => {
-                {{#useHttpClient}}formParams = {{/useHttpClient}}formParams.append('{{baseName}}', <any>element){{#useHttpClient}} || formParams{{/useHttpClient}};
+                {{#useHttpClient}}formParams = {{/useHttpClient}}append(formParams, '{{baseName}}', <any>element);
             })
         {{/isCollectionFormatMulti}}
         {{^isCollectionFormatMulti}}
-            {{#useHttpClient}}formParams = {{/useHttpClient}}formParams.append('{{baseName}}', {{paramName}}.join(COLLECTION_FORMATS['{{collectionFormat}}'])){{#useHttpClient}} || formParams{{/useHttpClient}};
+            {{#useHttpClient}}formParams = {{/useHttpClient}}append(formParams, '{{baseName}}', {{paramName}}.join(COLLECTION_FORMATS['{{collectionFormat}}']));
         {{/isCollectionFormatMulti}}
         }
         {{/isListContainer}}
         {{^isListContainer}}
         if ({{paramName}} !== undefined) {
-            {{#useHttpClient}}formParams = {{/useHttpClient}}formParams.append('{{baseName}}', <any>{{paramName}}){{#useHttpClient}} || formParams{{/useHttpClient}};
+            {{#useHttpClient}}formParams = {{/useHttpClient}}append(formParams, '{{baseName}}', <any>{{paramName}});
         }
         {{/isListContainer}}
 {{/formParams}}
@@ -353,4 +371,4 @@ export class {{classname}} {
     }
 
 {{/operation}}}
-{{/operations}}
+{{/operations}}
\ No newline at end of file
diff --git a/samples/client/petstore-security-test/typescript-angular/.swagger-codegen/VERSION b/samples/client/petstore-security-test/typescript-angular/.swagger-codegen/VERSION
index 855ff9501eb..017674fb59d 100644
--- a/samples/client/petstore-security-test/typescript-angular/.swagger-codegen/VERSION
+++ b/samples/client/petstore-security-test/typescript-angular/.swagger-codegen/VERSION
@@ -1 +1 @@
-2.4.0-SNAPSHOT
\ No newline at end of file
+2.4.3-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore-security-test/typescript-angular/README.md b/samples/client/petstore-security-test/typescript-angular/README.md
index f679bcb1320..9c7753a47b7 100644
--- a/samples/client/petstore-security-test/typescript-angular/README.md
+++ b/samples/client/petstore-security-test/typescript-angular/README.md
@@ -2,7 +2,7 @@
 
 ### Building
 
-To build an compile the typescript sources to javascript use:
+To install the required dependencies and to build the typescript sources run:
 ```
 npm install
 npm run build
@@ -14,7 +14,7 @@ First build the package than run ```npm publish```
 
 ### consuming
 
-navigate to the folder of your consuming project and run one of next commando's.
+Navigate to the folder of your consuming project and run one of next commands.
 
 _published:_
 
@@ -22,7 +22,7 @@ _published:_
 npm install @ --save
 ```
 
-_unPublished (not recommended):_
+_without publishing (not recommended):_
 
 ```
 npm install PATH_TO_GENERATED_PACKAGE --save
@@ -37,9 +37,16 @@ npm link
 
 In your project:
 ```
-npm link @
+npm link 
 ```
 
+__Note for Windows users:__ The Angular CLI has troubles to use linked npm packages.
+Please refer to this issue https://github.com/angular/angular-cli/issues/8284 for a solution / workaround.
+Published packages are not effected by this issue.
+
+
+#### General usage
+
 In your Angular project:
 
 
diff --git a/samples/client/petstore-security-test/typescript-angular/api.module.ts b/samples/client/petstore-security-test/typescript-angular/api.module.ts
index a95cda25231..867cee5c7b2 100644
--- a/samples/client/petstore-security-test/typescript-angular/api.module.ts
+++ b/samples/client/petstore-security-test/typescript-angular/api.module.ts
@@ -17,7 +17,7 @@ export class ApiModule {
         return {
             ngModule: ApiModule,
             providers: [ { provide: Configuration, useFactory: configurationFactory } ]
-        }
+        };
     }
 
     constructor( @Optional() @SkipSelf() parentModule: ApiModule,
diff --git a/samples/client/petstore-security-test/typescript-angular/api/fake.service.ts b/samples/client/petstore-security-test/typescript-angular/api/fake.service.ts
index d0047d78bee..cdfb5746278 100644
--- a/samples/client/petstore-security-test/typescript-angular/api/fake.service.ts
+++ b/samples/client/petstore-security-test/typescript-angular/api/fake.service.ts
@@ -22,6 +22,17 @@ import { Observable }                                        from 'rxjs/Observab
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+    import { HttpClient, HttpHeaders, HttpParams,
+    HttpResponse, HttpEvent }                           from '@angular/common/http';
+    import { CustomHttpUrlEncodingCodec }                        from '../encoder';
+
+
+type FormParams = URLSearchParams | FormData | HttpParams;
+
+function append(formParams: FormParams, param: string, value: any) {
+    return formParams.append(param, value)
+};
+
 
 @Injectable()
 export class FakeService {
@@ -46,7 +57,7 @@ export class FakeService {
      */
     private canConsumeForm(consumes: string[]): boolean {
         const form = 'multipart/form-data';
-        for (let consume of consumes) {
+        for (const consume of consumes) {
             if (form === consume) {
                 return true;
             }
@@ -67,6 +78,7 @@ export class FakeService {
     public testCodeInjectEndRnNR(testCodeInjectEndRnNR?: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public testCodeInjectEndRnNR(testCodeInjectEndRnNR?: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
 
+
         let headers = this.defaultHeaders;
 
         // to determine the Accept header
@@ -74,20 +86,20 @@ export class FakeService {
             'application/json',
             '*_/   =end --       '
         ];
-        let httpHeaderAcceptSelected: string | undefined = this.configuration.selectHeaderAccept(httpHeaderAccepts);
+        const httpHeaderAcceptSelected: string | undefined = this.configuration.selectHeaderAccept(httpHeaderAccepts);
         if (httpHeaderAcceptSelected != undefined) {
-            headers = headers.set("Accept", httpHeaderAcceptSelected);
+            headers = headers.set('Accept', httpHeaderAcceptSelected);
         }
 
         // to determine the Content-Type header
-        let consumes: string[] = [
+        const consumes: string[] = [
             'application/json',
             '*_/   =end --       '
         ];
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
@@ -95,9 +107,8 @@ export class FakeService {
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
         }
-
         if (testCodeInjectEndRnNR !== undefined) {
-            formParams = formParams.append('test code inject */ &#39; &quot; &#x3D;end -- \r\n \n \r', <any>testCodeInjectEndRnNR) || formParams;
+            formParams = append(formParams, 'test code inject */ &#39; &quot; &#x3D;end -- \r\n \n \r', <any>testCodeInjectEndRnNR);
         }
 
         return this.httpClient.put<any>(`${this.basePath}/fake`,
diff --git a/samples/client/petstore-security-test/typescript-angular/configuration.ts b/samples/client/petstore-security-test/typescript-angular/configuration.ts
index 2ee1824f5f7..82e8458f39e 100644
--- a/samples/client/petstore-security-test/typescript-angular/configuration.ts
+++ b/samples/client/petstore-security-test/typescript-angular/configuration.ts
@@ -28,8 +28,8 @@ export class Configuration {
      * Select the correct content-type to use for a request.
      * Uses {@link Configuration#isJsonMime} to determine the correct content-type.
      * If no content type is found return the first found type if the contentTypes is not empty
-     * @param {string[]} contentTypes - the array of content types that are available for selection
-     * @returns {string} the selected content-type or <code>undefined</code> if no selection could be made.
+     * @param contentTypes - the array of content types that are available for selection
+     * @returns the selected content-type or <code>undefined</code> if no selection could be made.
      */
     public selectHeaderContentType (contentTypes: string[]): string | undefined {
         if (contentTypes.length == 0) {
@@ -47,8 +47,8 @@ export class Configuration {
      * Select the correct accept content-type to use for a request.
      * Uses {@link Configuration#isJsonMime} to determine the correct accept content-type.
      * If no content type is found return the first found type if the contentTypes is not empty
-     * @param {string[]} accepts - the array of content types that are available for selection.
-     * @returns {string} the selected content-type or <code>undefined</code> if no selection could be made.
+     * @param accepts - the array of content types that are available for selection.
+     * @returns the selected content-type or <code>undefined</code> if no selection could be made.
      */
     public selectHeaderAccept(accepts: string[]): string | undefined {
         if (accepts.length == 0) {
@@ -69,8 +69,8 @@ export class Configuration {
      *   application/json; charset=UTF8
      *   APPLICATION/JSON
      *   application/vnd.company+json
-     * @param {string} mime - MIME (Multipurpose Internet Mail Extensions)
-     * @return {boolean} True if the given MIME is JSON, false otherwise.
+     * @param mime - MIME (Multipurpose Internet Mail Extensions)
+     * @return True if the given MIME is JSON, false otherwise.
      */
     public isJsonMime(mime: string): boolean {
         const jsonMime: RegExp = new RegExp('^(application\/json|[^;/ \t]+\/[^;/ \t]+[+]json)[ \t]*(;.*)?$', 'i');
diff --git a/samples/client/petstore/typescript-angular-v2/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v2/default/api/pet.service.ts
index 78080a33ea2..ee187c89cd0 100644
--- a/samples/client/petstore/typescript-angular-v2/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v2/default/api/pet.service.ts
@@ -26,6 +26,12 @@ import { Pet } from '../model/pet';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class PetService {
@@ -557,7 +563,8 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
@@ -569,12 +576,11 @@ export class PetService {
             // set the content-type explicitly to avoid having it set to 'text/plain'
             headers.set('Content-Type', 'application/x-www-form-urlencoded;charset=UTF-8');
         }
-
         if (name !== undefined) {
-            formParams.append('name', <any>name);
+            append(formParams, 'name', <any>name);
         }
         if (status !== undefined) {
-            formParams.append('status', <any>status);
+            append(formParams, 'status', <any>status);
         }
 
         let requestOptions: RequestOptionsArgs = new RequestOptions({
@@ -633,7 +639,8 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         // use FormData to transmit files using content-type "multipart/form-data"
@@ -648,12 +655,11 @@ export class PetService {
             // set the content-type explicitly to avoid having it set to 'text/plain'
             headers.set('Content-Type', 'application/x-www-form-urlencoded;charset=UTF-8');
         }
-
         if (additionalMetadata !== undefined) {
-            formParams.append('additionalMetadata', <any>additionalMetadata);
+            append(formParams, 'additionalMetadata', <any>additionalMetadata);
         }
         if (file !== undefined) {
-            formParams.append('file', <any>file);
+            append(formParams, 'file', <any>file);
         }
 
         let requestOptions: RequestOptionsArgs = new RequestOptions({
diff --git a/samples/client/petstore/typescript-angular-v2/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v2/default/api/store.service.ts
index fa78d49386a..559f8d9286b 100644
--- a/samples/client/petstore/typescript-angular-v2/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v2/default/api/store.service.ts
@@ -25,6 +25,12 @@ import { Order } from '../model/order';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class StoreService {
diff --git a/samples/client/petstore/typescript-angular-v2/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v2/default/api/user.service.ts
index 2d4286f42f1..047894acf77 100644
--- a/samples/client/petstore/typescript-angular-v2/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v2/default/api/user.service.ts
@@ -25,6 +25,12 @@ import { User } from '../model/user';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class UserService {
diff --git a/samples/client/petstore/typescript-angular-v2/npm/api/pet.service.ts b/samples/client/petstore/typescript-angular-v2/npm/api/pet.service.ts
index 78080a33ea2..ee187c89cd0 100644
--- a/samples/client/petstore/typescript-angular-v2/npm/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v2/npm/api/pet.service.ts
@@ -26,6 +26,12 @@ import { Pet } from '../model/pet';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class PetService {
@@ -557,7 +563,8 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
@@ -569,12 +576,11 @@ export class PetService {
             // set the content-type explicitly to avoid having it set to 'text/plain'
             headers.set('Content-Type', 'application/x-www-form-urlencoded;charset=UTF-8');
         }
-
         if (name !== undefined) {
-            formParams.append('name', <any>name);
+            append(formParams, 'name', <any>name);
         }
         if (status !== undefined) {
-            formParams.append('status', <any>status);
+            append(formParams, 'status', <any>status);
         }
 
         let requestOptions: RequestOptionsArgs = new RequestOptions({
@@ -633,7 +639,8 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         // use FormData to transmit files using content-type "multipart/form-data"
@@ -648,12 +655,11 @@ export class PetService {
             // set the content-type explicitly to avoid having it set to 'text/plain'
             headers.set('Content-Type', 'application/x-www-form-urlencoded;charset=UTF-8');
         }
-
         if (additionalMetadata !== undefined) {
-            formParams.append('additionalMetadata', <any>additionalMetadata);
+            append(formParams, 'additionalMetadata', <any>additionalMetadata);
         }
         if (file !== undefined) {
-            formParams.append('file', <any>file);
+            append(formParams, 'file', <any>file);
         }
 
         let requestOptions: RequestOptionsArgs = new RequestOptions({
diff --git a/samples/client/petstore/typescript-angular-v2/npm/api/store.service.ts b/samples/client/petstore/typescript-angular-v2/npm/api/store.service.ts
index fa78d49386a..559f8d9286b 100644
--- a/samples/client/petstore/typescript-angular-v2/npm/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v2/npm/api/store.service.ts
@@ -25,6 +25,12 @@ import { Order } from '../model/order';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class StoreService {
diff --git a/samples/client/petstore/typescript-angular-v2/npm/api/user.service.ts b/samples/client/petstore/typescript-angular-v2/npm/api/user.service.ts
index 2d4286f42f1..047894acf77 100644
--- a/samples/client/petstore/typescript-angular-v2/npm/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v2/npm/api/user.service.ts
@@ -25,6 +25,12 @@ import { User } from '../model/user';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class UserService {
diff --git a/samples/client/petstore/typescript-angular-v2/with-interfaces/api/pet.service.ts b/samples/client/petstore/typescript-angular-v2/with-interfaces/api/pet.service.ts
index f3caaf58a5b..e2363deed4d 100644
--- a/samples/client/petstore/typescript-angular-v2/with-interfaces/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v2/with-interfaces/api/pet.service.ts
@@ -27,6 +27,12 @@ import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables'
 import { Configuration }                                     from '../configuration';
 import { PetServiceInterface }                            from './pet.serviceInterface';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class PetService implements PetServiceInterface {
@@ -558,7 +564,8 @@ export class PetService implements PetServiceInterface {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
@@ -570,12 +577,11 @@ export class PetService implements PetServiceInterface {
             // set the content-type explicitly to avoid having it set to 'text/plain'
             headers.set('Content-Type', 'application/x-www-form-urlencoded;charset=UTF-8');
         }
-
         if (name !== undefined) {
-            formParams.append('name', <any>name);
+            append(formParams, 'name', <any>name);
         }
         if (status !== undefined) {
-            formParams.append('status', <any>status);
+            append(formParams, 'status', <any>status);
         }
 
         let requestOptions: RequestOptionsArgs = new RequestOptions({
@@ -634,7 +640,8 @@ export class PetService implements PetServiceInterface {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         // use FormData to transmit files using content-type "multipart/form-data"
@@ -649,12 +656,11 @@ export class PetService implements PetServiceInterface {
             // set the content-type explicitly to avoid having it set to 'text/plain'
             headers.set('Content-Type', 'application/x-www-form-urlencoded;charset=UTF-8');
         }
-
         if (additionalMetadata !== undefined) {
-            formParams.append('additionalMetadata', <any>additionalMetadata);
+            append(formParams, 'additionalMetadata', <any>additionalMetadata);
         }
         if (file !== undefined) {
-            formParams.append('file', <any>file);
+            append(formParams, 'file', <any>file);
         }
 
         let requestOptions: RequestOptionsArgs = new RequestOptions({
diff --git a/samples/client/petstore/typescript-angular-v2/with-interfaces/api/store.service.ts b/samples/client/petstore/typescript-angular-v2/with-interfaces/api/store.service.ts
index 9c34dc32632..d62ef57a51d 100644
--- a/samples/client/petstore/typescript-angular-v2/with-interfaces/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v2/with-interfaces/api/store.service.ts
@@ -26,6 +26,12 @@ import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables'
 import { Configuration }                                     from '../configuration';
 import { StoreServiceInterface }                            from './store.serviceInterface';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class StoreService implements StoreServiceInterface {
diff --git a/samples/client/petstore/typescript-angular-v2/with-interfaces/api/user.service.ts b/samples/client/petstore/typescript-angular-v2/with-interfaces/api/user.service.ts
index b093e70e7e2..5a304772450 100644
--- a/samples/client/petstore/typescript-angular-v2/with-interfaces/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v2/with-interfaces/api/user.service.ts
@@ -26,6 +26,12 @@ import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables'
 import { Configuration }                                     from '../configuration';
 import { UserServiceInterface }                            from './user.serviceInterface';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class UserService implements UserServiceInterface {
diff --git a/samples/client/petstore/typescript-angular-v4.3/npm/api/pet.service.ts b/samples/client/petstore/typescript-angular-v4.3/npm/api/pet.service.ts
index b3b51af413d..d3d36089ec3 100644
--- a/samples/client/petstore/typescript-angular-v4.3/npm/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v4.3/npm/api/pet.service.ts
@@ -24,6 +24,12 @@ import { Pet } from '../model/pet';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class PetService {
@@ -432,20 +438,21 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
             formParams = new FormData();
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
+            append = getAppender(true);
         }
-
         if (name !== undefined) {
-            formParams = formParams.append('name', <any>name) || formParams;
+            formParams = append(formParams, 'name', <any>name);
         }
         if (status !== undefined) {
-            formParams = formParams.append('status', <any>status) || formParams;
+            formParams = append(formParams, 'status', <any>status);
         }
 
         return this.httpClient.post<any>(`${this.basePath}/pet/${encodeURIComponent(String(petId))}`,
@@ -505,7 +512,8 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         // use FormData to transmit files using content-type "multipart/form-data"
@@ -515,13 +523,13 @@ export class PetService {
             formParams = new FormData();
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
+            append = getAppender(true);
         }
-
         if (additionalMetadata !== undefined) {
-            formParams = formParams.append('additionalMetadata', <any>additionalMetadata) || formParams;
+            formParams = append(formParams, 'additionalMetadata', <any>additionalMetadata);
         }
         if (file !== undefined) {
-            formParams = formParams.append('file', <any>file) || formParams;
+            formParams = append(formParams, 'file', <any>file);
         }
 
         return this.httpClient.post<ApiResponse>(`${this.basePath}/pet/${encodeURIComponent(String(petId))}/uploadImage`,
diff --git a/samples/client/petstore/typescript-angular-v4.3/npm/api/store.service.ts b/samples/client/petstore/typescript-angular-v4.3/npm/api/store.service.ts
index 22f13b6f1bb..25241499b5b 100644
--- a/samples/client/petstore/typescript-angular-v4.3/npm/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v4.3/npm/api/store.service.ts
@@ -23,6 +23,12 @@ import { Order } from '../model/order';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class StoreService {
diff --git a/samples/client/petstore/typescript-angular-v4.3/npm/api/user.service.ts b/samples/client/petstore/typescript-angular-v4.3/npm/api/user.service.ts
index e1323ce454b..26ace0707e5 100644
--- a/samples/client/petstore/typescript-angular-v4.3/npm/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v4.3/npm/api/user.service.ts
@@ -23,6 +23,12 @@ import { User } from '../model/user';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class UserService {
diff --git a/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/pet.service.ts b/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/pet.service.ts
index a922b13249f..24542324765 100644
--- a/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/pet.service.ts
@@ -25,6 +25,12 @@ import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables'
 import { Configuration }                                     from '../configuration';
 import { PetServiceInterface }                            from './pet.serviceInterface';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class PetService implements PetServiceInterface {
@@ -433,20 +439,21 @@ export class PetService implements PetServiceInterface {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
             formParams = new FormData();
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
+            append = getAppender(true);
         }
-
         if (name !== undefined) {
-            formParams = formParams.append('name', <any>name) || formParams;
+            formParams = append(formParams, 'name', <any>name);
         }
         if (status !== undefined) {
-            formParams = formParams.append('status', <any>status) || formParams;
+            formParams = append(formParams, 'status', <any>status);
         }
 
         return this.httpClient.post<any>(`${this.basePath}/pet/${encodeURIComponent(String(petId))}`,
@@ -506,7 +513,8 @@ export class PetService implements PetServiceInterface {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         // use FormData to transmit files using content-type "multipart/form-data"
@@ -516,13 +524,13 @@ export class PetService implements PetServiceInterface {
             formParams = new FormData();
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
+            append = getAppender(true);
         }
-
         if (additionalMetadata !== undefined) {
-            formParams = formParams.append('additionalMetadata', <any>additionalMetadata) || formParams;
+            formParams = append(formParams, 'additionalMetadata', <any>additionalMetadata);
         }
         if (file !== undefined) {
-            formParams = formParams.append('file', <any>file) || formParams;
+            formParams = append(formParams, 'file', <any>file);
         }
 
         return this.httpClient.post<ApiResponse>(`${this.basePath}/pet/${encodeURIComponent(String(petId))}/uploadImage`,
diff --git a/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/store.service.ts b/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/store.service.ts
index 271fabb7ba8..59abfbfb980 100644
--- a/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/store.service.ts
@@ -24,6 +24,12 @@ import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables'
 import { Configuration }                                     from '../configuration';
 import { StoreServiceInterface }                            from './store.serviceInterface';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class StoreService implements StoreServiceInterface {
diff --git a/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/user.service.ts b/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/user.service.ts
index 491402e119a..5cf120e6431 100644
--- a/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v4.3/with-interfaces/api/user.service.ts
@@ -24,6 +24,12 @@ import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables'
 import { Configuration }                                     from '../configuration';
 import { UserServiceInterface }                            from './user.serviceInterface';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class UserService implements UserServiceInterface {
diff --git a/samples/client/petstore/typescript-angular-v4/npm/api/pet.service.ts b/samples/client/petstore/typescript-angular-v4/npm/api/pet.service.ts
index 78080a33ea2..ee187c89cd0 100644
--- a/samples/client/petstore/typescript-angular-v4/npm/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v4/npm/api/pet.service.ts
@@ -26,6 +26,12 @@ import { Pet } from '../model/pet';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class PetService {
@@ -557,7 +563,8 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
@@ -569,12 +576,11 @@ export class PetService {
             // set the content-type explicitly to avoid having it set to 'text/plain'
             headers.set('Content-Type', 'application/x-www-form-urlencoded;charset=UTF-8');
         }
-
         if (name !== undefined) {
-            formParams.append('name', <any>name);
+            append(formParams, 'name', <any>name);
         }
         if (status !== undefined) {
-            formParams.append('status', <any>status);
+            append(formParams, 'status', <any>status);
         }
 
         let requestOptions: RequestOptionsArgs = new RequestOptions({
@@ -633,7 +639,8 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         // use FormData to transmit files using content-type "multipart/form-data"
@@ -648,12 +655,11 @@ export class PetService {
             // set the content-type explicitly to avoid having it set to 'text/plain'
             headers.set('Content-Type', 'application/x-www-form-urlencoded;charset=UTF-8');
         }
-
         if (additionalMetadata !== undefined) {
-            formParams.append('additionalMetadata', <any>additionalMetadata);
+            append(formParams, 'additionalMetadata', <any>additionalMetadata);
         }
         if (file !== undefined) {
-            formParams.append('file', <any>file);
+            append(formParams, 'file', <any>file);
         }
 
         let requestOptions: RequestOptionsArgs = new RequestOptions({
diff --git a/samples/client/petstore/typescript-angular-v4/npm/api/store.service.ts b/samples/client/petstore/typescript-angular-v4/npm/api/store.service.ts
index fa78d49386a..559f8d9286b 100644
--- a/samples/client/petstore/typescript-angular-v4/npm/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v4/npm/api/store.service.ts
@@ -25,6 +25,12 @@ import { Order } from '../model/order';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class StoreService {
diff --git a/samples/client/petstore/typescript-angular-v4/npm/api/user.service.ts b/samples/client/petstore/typescript-angular-v4/npm/api/user.service.ts
index 2d4286f42f1..047894acf77 100644
--- a/samples/client/petstore/typescript-angular-v4/npm/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v4/npm/api/user.service.ts
@@ -25,6 +25,12 @@ import { User } from '../model/user';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class UserService {
diff --git a/samples/client/petstore/typescript-angular-v5/npm/api/pet.service.ts b/samples/client/petstore/typescript-angular-v5/npm/api/pet.service.ts
index 18563adb1b3..d3d36089ec3 100644
--- a/samples/client/petstore/typescript-angular-v5/npm/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v5/npm/api/pet.service.ts
@@ -24,6 +24,12 @@ import { Pet } from '../model/pet';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class PetService {
@@ -68,6 +74,7 @@ export class PetService {
     public addPet(body: Pet, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public addPet(body: Pet, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public addPet(body: Pet, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling addPet.');
         }
@@ -125,10 +132,12 @@ export class PetService {
     public deletePet(petId: number, apiKey?: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public deletePet(petId: number, apiKey?: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public deletePet(petId: number, apiKey?: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (petId === null || petId === undefined) {
             throw new Error('Required parameter petId was null or undefined when calling deletePet.');
         }
 
+
         let headers = this.defaultHeaders;
         if (apiKey !== undefined && apiKey !== null) {
             headers = headers.set('api_key', String(apiKey));
@@ -177,6 +186,7 @@ export class PetService {
     public findPetsByStatus(status: Array<'available' | 'pending' | 'sold'>, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<Array<Pet>>>;
     public findPetsByStatus(status: Array<'available' | 'pending' | 'sold'>, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<Array<Pet>>>;
     public findPetsByStatus(status: Array<'available' | 'pending' | 'sold'>, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (status === null || status === undefined) {
             throw new Error('Required parameter status was null or undefined when calling findPetsByStatus.');
         }
@@ -232,6 +242,7 @@ export class PetService {
     public findPetsByTags(tags: Array<string>, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<Array<Pet>>>;
     public findPetsByTags(tags: Array<string>, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<Array<Pet>>>;
     public findPetsByTags(tags: Array<string>, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (tags === null || tags === undefined) {
             throw new Error('Required parameter tags was null or undefined when calling findPetsByTags.');
         }
@@ -287,6 +298,7 @@ export class PetService {
     public getPetById(petId: number, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<Pet>>;
     public getPetById(petId: number, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<Pet>>;
     public getPetById(petId: number, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (petId === null || petId === undefined) {
             throw new Error('Required parameter petId was null or undefined when calling getPetById.');
         }
@@ -333,6 +345,7 @@ export class PetService {
     public updatePet(body: Pet, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public updatePet(body: Pet, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public updatePet(body: Pet, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling updatePet.');
         }
@@ -391,10 +404,13 @@ export class PetService {
     public updatePetWithForm(petId: number, name?: string, status?: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public updatePetWithForm(petId: number, name?: string, status?: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public updatePetWithForm(petId: number, name?: string, status?: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (petId === null || petId === undefined) {
             throw new Error('Required parameter petId was null or undefined when calling updatePetWithForm.');
         }
 
+
+
         let headers = this.defaultHeaders;
 
         // authentication (petstore_auth) required
@@ -422,20 +438,21 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
             formParams = new FormData();
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
+            append = getAppender(true);
         }
-
         if (name !== undefined) {
-            formParams = formParams.append('name', <any>name) || formParams;
+            formParams = append(formParams, 'name', <any>name);
         }
         if (status !== undefined) {
-            formParams = formParams.append('status', <any>status) || formParams;
+            formParams = append(formParams, 'status', <any>status);
         }
 
         return this.httpClient.post<any>(`${this.basePath}/pet/${encodeURIComponent(String(petId))}`,
@@ -462,10 +479,13 @@ export class PetService {
     public uploadFile(petId: number, additionalMetadata?: string, file?: Blob, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<ApiResponse>>;
     public uploadFile(petId: number, additionalMetadata?: string, file?: Blob, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<ApiResponse>>;
     public uploadFile(petId: number, additionalMetadata?: string, file?: Blob, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (petId === null || petId === undefined) {
             throw new Error('Required parameter petId was null or undefined when calling uploadFile.');
         }
 
+
+
         let headers = this.defaultHeaders;
 
         // authentication (petstore_auth) required
@@ -492,7 +512,8 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         // use FormData to transmit files using content-type "multipart/form-data"
@@ -502,13 +523,13 @@ export class PetService {
             formParams = new FormData();
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
+            append = getAppender(true);
         }
-
         if (additionalMetadata !== undefined) {
-            formParams = formParams.append('additionalMetadata', <any>additionalMetadata) || formParams;
+            formParams = append(formParams, 'additionalMetadata', <any>additionalMetadata);
         }
         if (file !== undefined) {
-            formParams = formParams.append('file', <any>file) || formParams;
+            formParams = append(formParams, 'file', <any>file);
         }
 
         return this.httpClient.post<ApiResponse>(`${this.basePath}/pet/${encodeURIComponent(String(petId))}/uploadImage`,
diff --git a/samples/client/petstore/typescript-angular-v5/npm/api/store.service.ts b/samples/client/petstore/typescript-angular-v5/npm/api/store.service.ts
index 03016b73c9d..25241499b5b 100644
--- a/samples/client/petstore/typescript-angular-v5/npm/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v5/npm/api/store.service.ts
@@ -23,6 +23,12 @@ import { Order } from '../model/order';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class StoreService {
@@ -67,6 +73,7 @@ export class StoreService {
     public deleteOrder(orderId: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public deleteOrder(orderId: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public deleteOrder(orderId: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (orderId === null || orderId === undefined) {
             throw new Error('Required parameter orderId was null or undefined when calling deleteOrder.');
         }
@@ -149,6 +156,7 @@ export class StoreService {
     public getOrderById(orderId: number, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<Order>>;
     public getOrderById(orderId: number, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<Order>>;
     public getOrderById(orderId: number, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (orderId === null || orderId === undefined) {
             throw new Error('Required parameter orderId was null or undefined when calling getOrderById.');
         }
@@ -190,6 +198,7 @@ export class StoreService {
     public placeOrder(body: Order, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<Order>>;
     public placeOrder(body: Order, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<Order>>;
     public placeOrder(body: Order, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling placeOrder.');
         }
diff --git a/samples/client/petstore/typescript-angular-v5/npm/api/user.service.ts b/samples/client/petstore/typescript-angular-v5/npm/api/user.service.ts
index 7c7ccda2a79..26ace0707e5 100644
--- a/samples/client/petstore/typescript-angular-v5/npm/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v5/npm/api/user.service.ts
@@ -23,6 +23,12 @@ import { User } from '../model/user';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class UserService {
@@ -67,6 +73,7 @@ export class UserService {
     public createUser(body: User, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public createUser(body: User, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public createUser(body: User, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling createUser.');
         }
@@ -113,6 +120,7 @@ export class UserService {
     public createUsersWithArrayInput(body: Array<User>, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public createUsersWithArrayInput(body: Array<User>, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public createUsersWithArrayInput(body: Array<User>, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling createUsersWithArrayInput.');
         }
@@ -159,6 +167,7 @@ export class UserService {
     public createUsersWithListInput(body: Array<User>, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public createUsersWithListInput(body: Array<User>, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public createUsersWithListInput(body: Array<User>, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling createUsersWithListInput.');
         }
@@ -205,6 +214,7 @@ export class UserService {
     public deleteUser(username: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public deleteUser(username: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public deleteUser(username: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (username === null || username === undefined) {
             throw new Error('Required parameter username was null or undefined when calling deleteUser.');
         }
@@ -246,6 +256,7 @@ export class UserService {
     public getUserByName(username: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<User>>;
     public getUserByName(username: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<User>>;
     public getUserByName(username: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (username === null || username === undefined) {
             throw new Error('Required parameter username was null or undefined when calling getUserByName.');
         }
@@ -288,9 +299,11 @@ export class UserService {
     public loginUser(username: string, password: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<string>>;
     public loginUser(username: string, password: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<string>>;
     public loginUser(username: string, password: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (username === null || username === undefined) {
             throw new Error('Required parameter username was null or undefined when calling loginUser.');
         }
+
         if (password === null || password === undefined) {
             throw new Error('Required parameter password was null or undefined when calling loginUser.');
         }
@@ -379,9 +392,11 @@ export class UserService {
     public updateUser(username: string, body: User, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public updateUser(username: string, body: User, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public updateUser(username: string, body: User, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (username === null || username === undefined) {
             throw new Error('Required parameter username was null or undefined when calling updateUser.');
         }
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling updateUser.');
         }
diff --git a/samples/client/petstore/typescript-angular-v5/npm/model/amount.ts b/samples/client/petstore/typescript-angular-v5/npm/model/amount.ts
new file mode 100644
index 00000000000..90fc5c01a30
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v5/npm/model/amount.ts
@@ -0,0 +1,24 @@
+/**
+ * Swagger Petstore
+ * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * OpenAPI spec version: 1.0.0
+ * Contact: apiteam@swagger.io
+ *
+ * NOTE: This class is auto generated by the swagger code generator program.
+ * https://github.com/swagger-api/swagger-codegen.git
+ * Do not edit the class manually.
+ */
+import { Currency } from './currency';
+
+
+/**
+ * some description 
+ */
+export interface Amount { 
+    /**
+     * some description 
+     */
+    value: number;
+    currency: Currency;
+}
diff --git a/samples/client/petstore/typescript-angular-v5/npm/model/currency.ts b/samples/client/petstore/typescript-angular-v5/npm/model/currency.ts
new file mode 100644
index 00000000000..c9ff596d4cb
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v5/npm/model/currency.ts
@@ -0,0 +1,17 @@
+/**
+ * Swagger Petstore
+ * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * OpenAPI spec version: 1.0.0
+ * Contact: apiteam@swagger.io
+ *
+ * NOTE: This class is auto generated by the swagger code generator program.
+ * https://github.com/swagger-api/swagger-codegen.git
+ * Do not edit the class manually.
+ */
+
+
+/**
+ * some description 
+ */
+export type Currency = string;
diff --git a/samples/client/petstore/typescript-angular-v5/npm/model/models.ts b/samples/client/petstore/typescript-angular-v5/npm/model/models.ts
index 8607c5dabd0..f6aebdbf709 100644
--- a/samples/client/petstore/typescript-angular-v5/npm/model/models.ts
+++ b/samples/client/petstore/typescript-angular-v5/npm/model/models.ts
@@ -1,5 +1,7 @@
+export * from './amount';
 export * from './apiResponse';
 export * from './category';
+export * from './currency';
 export * from './order';
 export * from './pet';
 export * from './tag';
diff --git a/samples/client/petstore/typescript-angular-v5/with-interfaces/api/pet.service.ts b/samples/client/petstore/typescript-angular-v5/with-interfaces/api/pet.service.ts
index a922b13249f..24542324765 100644
--- a/samples/client/petstore/typescript-angular-v5/with-interfaces/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v5/with-interfaces/api/pet.service.ts
@@ -25,6 +25,12 @@ import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables'
 import { Configuration }                                     from '../configuration';
 import { PetServiceInterface }                            from './pet.serviceInterface';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class PetService implements PetServiceInterface {
@@ -433,20 +439,21 @@ export class PetService implements PetServiceInterface {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
             formParams = new FormData();
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
+            append = getAppender(true);
         }
-
         if (name !== undefined) {
-            formParams = formParams.append('name', <any>name) || formParams;
+            formParams = append(formParams, 'name', <any>name);
         }
         if (status !== undefined) {
-            formParams = formParams.append('status', <any>status) || formParams;
+            formParams = append(formParams, 'status', <any>status);
         }
 
         return this.httpClient.post<any>(`${this.basePath}/pet/${encodeURIComponent(String(petId))}`,
@@ -506,7 +513,8 @@ export class PetService implements PetServiceInterface {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         // use FormData to transmit files using content-type "multipart/form-data"
@@ -516,13 +524,13 @@ export class PetService implements PetServiceInterface {
             formParams = new FormData();
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
+            append = getAppender(true);
         }
-
         if (additionalMetadata !== undefined) {
-            formParams = formParams.append('additionalMetadata', <any>additionalMetadata) || formParams;
+            formParams = append(formParams, 'additionalMetadata', <any>additionalMetadata);
         }
         if (file !== undefined) {
-            formParams = formParams.append('file', <any>file) || formParams;
+            formParams = append(formParams, 'file', <any>file);
         }
 
         return this.httpClient.post<ApiResponse>(`${this.basePath}/pet/${encodeURIComponent(String(petId))}/uploadImage`,
diff --git a/samples/client/petstore/typescript-angular-v5/with-interfaces/api/store.service.ts b/samples/client/petstore/typescript-angular-v5/with-interfaces/api/store.service.ts
index 271fabb7ba8..59abfbfb980 100644
--- a/samples/client/petstore/typescript-angular-v5/with-interfaces/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v5/with-interfaces/api/store.service.ts
@@ -24,6 +24,12 @@ import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables'
 import { Configuration }                                     from '../configuration';
 import { StoreServiceInterface }                            from './store.serviceInterface';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class StoreService implements StoreServiceInterface {
diff --git a/samples/client/petstore/typescript-angular-v5/with-interfaces/api/user.service.ts b/samples/client/petstore/typescript-angular-v5/with-interfaces/api/user.service.ts
index 491402e119a..5cf120e6431 100644
--- a/samples/client/petstore/typescript-angular-v5/with-interfaces/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v5/with-interfaces/api/user.service.ts
@@ -24,6 +24,12 @@ import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables'
 import { Configuration }                                     from '../configuration';
 import { UserServiceInterface }                            from './user.serviceInterface';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class UserService implements UserServiceInterface {
diff --git a/samples/client/petstore/typescript-angular-v6/npm/api/pet.service.ts b/samples/client/petstore/typescript-angular-v6/npm/api/pet.service.ts
index d62314aefe5..caef4a0d383 100644
--- a/samples/client/petstore/typescript-angular-v6/npm/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v6/npm/api/pet.service.ts
@@ -24,6 +24,12 @@ import { Pet } from '../model/pet';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class PetService {
@@ -68,6 +74,7 @@ export class PetService {
     public addPet(body: Pet, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public addPet(body: Pet, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public addPet(body: Pet, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling addPet.');
         }
@@ -125,10 +132,12 @@ export class PetService {
     public deletePet(petId: number, apiKey?: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public deletePet(petId: number, apiKey?: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public deletePet(petId: number, apiKey?: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (petId === null || petId === undefined) {
             throw new Error('Required parameter petId was null or undefined when calling deletePet.');
         }
 
+
         let headers = this.defaultHeaders;
         if (apiKey !== undefined && apiKey !== null) {
             headers = headers.set('api_key', String(apiKey));
@@ -177,6 +186,7 @@ export class PetService {
     public findPetsByStatus(status: Array<'available' | 'pending' | 'sold'>, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<Array<Pet>>>;
     public findPetsByStatus(status: Array<'available' | 'pending' | 'sold'>, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<Array<Pet>>>;
     public findPetsByStatus(status: Array<'available' | 'pending' | 'sold'>, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (status === null || status === undefined) {
             throw new Error('Required parameter status was null or undefined when calling findPetsByStatus.');
         }
@@ -232,6 +242,7 @@ export class PetService {
     public findPetsByTags(tags: Array<string>, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<Array<Pet>>>;
     public findPetsByTags(tags: Array<string>, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<Array<Pet>>>;
     public findPetsByTags(tags: Array<string>, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (tags === null || tags === undefined) {
             throw new Error('Required parameter tags was null or undefined when calling findPetsByTags.');
         }
@@ -287,6 +298,7 @@ export class PetService {
     public getPetById(petId: number, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<Pet>>;
     public getPetById(petId: number, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<Pet>>;
     public getPetById(petId: number, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (petId === null || petId === undefined) {
             throw new Error('Required parameter petId was null or undefined when calling getPetById.');
         }
@@ -333,6 +345,7 @@ export class PetService {
     public updatePet(body: Pet, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public updatePet(body: Pet, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public updatePet(body: Pet, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling updatePet.');
         }
@@ -391,10 +404,13 @@ export class PetService {
     public updatePetWithForm(petId: number, name?: string, status?: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public updatePetWithForm(petId: number, name?: string, status?: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public updatePetWithForm(petId: number, name?: string, status?: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (petId === null || petId === undefined) {
             throw new Error('Required parameter petId was null or undefined when calling updatePetWithForm.');
         }
 
+
+
         let headers = this.defaultHeaders;
 
         // authentication (petstore_auth) required
@@ -422,20 +438,21 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
             formParams = new FormData();
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
+            append = getAppender(true);
         }
-
         if (name !== undefined) {
-            formParams = formParams.append('name', <any>name) || formParams;
+            formParams = append(formParams, 'name', <any>name);
         }
         if (status !== undefined) {
-            formParams = formParams.append('status', <any>status) || formParams;
+            formParams = append(formParams, 'status', <any>status);
         }
 
         return this.httpClient.post<any>(`${this.basePath}/pet/${encodeURIComponent(String(petId))}`,
@@ -462,10 +479,13 @@ export class PetService {
     public uploadFile(petId: number, additionalMetadata?: string, file?: Blob, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<ApiResponse>>;
     public uploadFile(petId: number, additionalMetadata?: string, file?: Blob, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<ApiResponse>>;
     public uploadFile(petId: number, additionalMetadata?: string, file?: Blob, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (petId === null || petId === undefined) {
             throw new Error('Required parameter petId was null or undefined when calling uploadFile.');
         }
 
+
+
         let headers = this.defaultHeaders;
 
         // authentication (petstore_auth) required
@@ -492,7 +512,8 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void; };
+        let formParams: FormParams;
+        let append = getAppender();
         let useForm = false;
         let convertFormParamsToString = false;
         // use FormData to transmit files using content-type "multipart/form-data"
@@ -502,13 +523,13 @@ export class PetService {
             formParams = new FormData();
         } else {
             formParams = new HttpParams({encoder: new CustomHttpUrlEncodingCodec()});
+            append = getAppender(true);
         }
-
         if (additionalMetadata !== undefined) {
-            formParams = formParams.append('additionalMetadata', <any>additionalMetadata) || formParams;
+            formParams = append(formParams, 'additionalMetadata', <any>additionalMetadata);
         }
         if (file !== undefined) {
-            formParams = formParams.append('file', <any>file) || formParams;
+            formParams = append(formParams, 'file', <any>file);
         }
 
         return this.httpClient.post<ApiResponse>(`${this.basePath}/pet/${encodeURIComponent(String(petId))}/uploadImage`,
diff --git a/samples/client/petstore/typescript-angular-v6/npm/api/store.service.ts b/samples/client/petstore/typescript-angular-v6/npm/api/store.service.ts
index c8e83fb6416..372f5fe1bd7 100644
--- a/samples/client/petstore/typescript-angular-v6/npm/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v6/npm/api/store.service.ts
@@ -23,6 +23,12 @@ import { Order } from '../model/order';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class StoreService {
@@ -67,6 +73,7 @@ export class StoreService {
     public deleteOrder(orderId: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public deleteOrder(orderId: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public deleteOrder(orderId: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (orderId === null || orderId === undefined) {
             throw new Error('Required parameter orderId was null or undefined when calling deleteOrder.');
         }
@@ -149,6 +156,7 @@ export class StoreService {
     public getOrderById(orderId: number, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<Order>>;
     public getOrderById(orderId: number, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<Order>>;
     public getOrderById(orderId: number, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (orderId === null || orderId === undefined) {
             throw new Error('Required parameter orderId was null or undefined when calling getOrderById.');
         }
@@ -190,6 +198,7 @@ export class StoreService {
     public placeOrder(body: Order, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<Order>>;
     public placeOrder(body: Order, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<Order>>;
     public placeOrder(body: Order, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling placeOrder.');
         }
diff --git a/samples/client/petstore/typescript-angular-v6/npm/api/user.service.ts b/samples/client/petstore/typescript-angular-v6/npm/api/user.service.ts
index c6ea28aa921..acb0066d250 100644
--- a/samples/client/petstore/typescript-angular-v6/npm/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v6/npm/api/user.service.ts
@@ -23,6 +23,12 @@ import { User } from '../model/user';
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
 
+type FormParams = HttpParams | URLSearchParams | FormData;
+
+function getAppender(useReturnValue = false) {
+    return (formParams: FormParams, param: string, value: any) =>
+    useReturnValue ? formParams.append(param, value) : formParams.append(param, value), formParams;
+}
 
 @Injectable()
 export class UserService {
@@ -67,6 +73,7 @@ export class UserService {
     public createUser(body: User, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public createUser(body: User, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public createUser(body: User, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling createUser.');
         }
@@ -113,6 +120,7 @@ export class UserService {
     public createUsersWithArrayInput(body: Array<User>, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public createUsersWithArrayInput(body: Array<User>, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public createUsersWithArrayInput(body: Array<User>, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling createUsersWithArrayInput.');
         }
@@ -159,6 +167,7 @@ export class UserService {
     public createUsersWithListInput(body: Array<User>, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public createUsersWithListInput(body: Array<User>, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public createUsersWithListInput(body: Array<User>, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling createUsersWithListInput.');
         }
@@ -205,6 +214,7 @@ export class UserService {
     public deleteUser(username: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public deleteUser(username: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public deleteUser(username: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (username === null || username === undefined) {
             throw new Error('Required parameter username was null or undefined when calling deleteUser.');
         }
@@ -246,6 +256,7 @@ export class UserService {
     public getUserByName(username: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<User>>;
     public getUserByName(username: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<User>>;
     public getUserByName(username: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (username === null || username === undefined) {
             throw new Error('Required parameter username was null or undefined when calling getUserByName.');
         }
@@ -288,9 +299,11 @@ export class UserService {
     public loginUser(username: string, password: string, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<string>>;
     public loginUser(username: string, password: string, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<string>>;
     public loginUser(username: string, password: string, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (username === null || username === undefined) {
             throw new Error('Required parameter username was null or undefined when calling loginUser.');
         }
+
         if (password === null || password === undefined) {
             throw new Error('Required parameter password was null or undefined when calling loginUser.');
         }
@@ -379,9 +392,11 @@ export class UserService {
     public updateUser(username: string, body: User, observe?: 'response', reportProgress?: boolean): Observable<HttpResponse<any>>;
     public updateUser(username: string, body: User, observe?: 'events', reportProgress?: boolean): Observable<HttpEvent<any>>;
     public updateUser(username: string, body: User, observe: any = 'body', reportProgress: boolean = false ): Observable<any> {
+
         if (username === null || username === undefined) {
             throw new Error('Required parameter username was null or undefined when calling updateUser.');
         }
+
         if (body === null || body === undefined) {
             throw new Error('Required parameter body was null or undefined when calling updateUser.');
         }
diff --git a/samples/client/petstore/typescript-angular-v6/npm/model/amount.ts b/samples/client/petstore/typescript-angular-v6/npm/model/amount.ts
new file mode 100644
index 00000000000..90fc5c01a30
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v6/npm/model/amount.ts
@@ -0,0 +1,24 @@
+/**
+ * Swagger Petstore
+ * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * OpenAPI spec version: 1.0.0
+ * Contact: apiteam@swagger.io
+ *
+ * NOTE: This class is auto generated by the swagger code generator program.
+ * https://github.com/swagger-api/swagger-codegen.git
+ * Do not edit the class manually.
+ */
+import { Currency } from './currency';
+
+
+/**
+ * some description 
+ */
+export interface Amount { 
+    /**
+     * some description 
+     */
+    value: number;
+    currency: Currency;
+}
diff --git a/samples/client/petstore/typescript-angular-v6/npm/model/currency.ts b/samples/client/petstore/typescript-angular-v6/npm/model/currency.ts
new file mode 100644
index 00000000000..c9ff596d4cb
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v6/npm/model/currency.ts
@@ -0,0 +1,17 @@
+/**
+ * Swagger Petstore
+ * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * OpenAPI spec version: 1.0.0
+ * Contact: apiteam@swagger.io
+ *
+ * NOTE: This class is auto generated by the swagger code generator program.
+ * https://github.com/swagger-api/swagger-codegen.git
+ * Do not edit the class manually.
+ */
+
+
+/**
+ * some description 
+ */
+export type Currency = string;
diff --git a/samples/client/petstore/typescript-angular-v6/npm/model/models.ts b/samples/client/petstore/typescript-angular-v6/npm/model/models.ts
index 8607c5dabd0..f6aebdbf709 100644
--- a/samples/client/petstore/typescript-angular-v6/npm/model/models.ts
+++ b/samples/client/petstore/typescript-angular-v6/npm/model/models.ts
@@ -1,5 +1,7 @@
+export * from './amount';
 export * from './apiResponse';
 export * from './category';
+export * from './currency';
 export * from './order';
 export * from './pet';
 export * from './tag';