/**
  * Check client is authorized.
  * @return bool
  * @throws Exception
  */
 public function getIsAuthorized()
 {
     if (!$this->_isAuthorized) {
         $client = $this->getResponseType()->getClient();
         $refreshToken = RefreshToken::findByClient($client);
         return $refreshToken != null;
     }
     return true;
 }