/**
  * Returns user profile data
  *
  * @param $id
  * @return array|null
  */
 public function getUserProfileData($id)
 {
     $userModel = $this->userStorage->getUserData($id);
     if ($userModel === null) {
         return null;
     }
     return ['email' => $userModel->email, 'created_at' => $userModel->created_at->toDateTimeString()];
 }
 /**
  * @inheritdoc
  */
 public function retrieveByCredentials(array $credentials)
 {
     return $this->userStorage->getByCredentials($credentials);
 }