Now with cleaner participants in the responses

ref #6

src/models/entities/UserGroup.ts

@@ -4,6 +4,8 @@ import {
   IsString
 } from "class-validator";
 import { ChildEntity, Column } from "typeorm";
+import { ResponsePrincipal } from '../responses/ResponsePrincipal';
+import { ResponseUserGroup } from '../responses/ResponseUserGroup';
 import { Principal } from './Principal';
 
 /**
@@ -27,4 +29,8 @@ export class UserGroup extends Principal {
   @IsOptional()
   @IsString()
   description?: string;
+
+  public toResponse(): ResponsePrincipal {
+    return new ResponseUserGroup(this);
+  }
 }