Implemented the interface in all responses

refr #132

src/models/responses/ResponseGroupContact.ts

@@ -1,12 +1,20 @@
 import { IsInt, IsObject, IsString } from "class-validator";
 import { Address } from '../entities/Address';
 import { GroupContact } from '../entities/GroupContact';
+import { ResponseObjectType } from '../enums/ResponseObjectType';
+import { IResponse } from './IResponse';
 import { ResponseRunnerGroup } from './ResponseRunnerGroup';
 
 /**
  * Defines the group contact response.
 */
-export class ResponseGroupContact {
+export class ResponseGroupContact implements IResponse {
+    /**
+    * The responseType.
+    * This contains the type of class/entity this response contains.
+    */
+    responseType: ResponseObjectType = ResponseObjectType.GROUPCONTACT;
+
     /**
      * The contact's id.
      */