Inheritance: extends Illuminate\Foundation\Http\FormRequest
 /**
  * Update the specified resource in storage.
  *
  * @param  UserUpdateRequest $request
  * @param  string $id
  *
  * @return Response
  */
 public function update(UserUpdateRequest $request, $id)
 {
     $this->validator->with($request->all())->passesOrFail(ValidatorInterface::RULE_UPDATE);
     $user = $this->repository->update($request->all(), $id);
     // throw exception if update failed
     //        throw new UpdateResourceFailedException('Failed to update.');
     // Updated, return 204 No Content
     return $this->response->noContent();
 }