updated sample

Author: HugoMario

samples/client/petstore/typescript-angular-v4/npm/.swagger-codegen/VERSION

@@ -1 +1 @@
-2.4.12-SNAPSHOT
+2.4.15-SNAPSHOT

samples/client/petstore/typescript-angular-v4/npm/api/pet.service.ts

@@ -557,7 +557,7 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void | HttpParams; };
+        let formParams: { append(param: string, value: any): void; };
         let useForm = false;
         let convertFormParamsToString = false;
         if (useForm) {
@@ -633,7 +633,7 @@ export class PetService {
 
         const canConsumeForm = this.canConsumeForm(consumes);
 
-        let formParams: { append(param: string, value: any): void | HttpParams; };
+        let formParams: { append(param: string, value: any): void; };
         let useForm = false;
         let convertFormParamsToString = false;
         // use FormData to transmit files using content-type "multipart/form-data"