private function getOAuth2Adapter($adapter_id, $state = null)
 {
     if (empty($adapter_id)) {
         return null;
     }
     try {
         $adapter = OAuth2::getAdapterInstance($adapter_id);
         $adapter->setState($state);
         return $adapter;
     } catch (OAuth2_Exception $ex) {
         $this->logException($ex);
         return null;
     }
 }