public static function method_findIdentifiersByMetadata($data, &$status)
 {
     if (!isset($data["key"]) || !isset($data["value"]) || !isset($data['userid'])) {
         $status = 400;
         return '';
     }
     $ucontroller = new sspmod_janus_UserController(SimpleSAML_Configuration::getConfig('module_janus.php'));
     $ucontroller->setUser($data['userid']);
     $entities = $ucontroller->searchEntitiesByMetadata($data['key'], $data['value']);
     $result = array();
     foreach ($entities as $entity) {
         $result[] = $entity->getentityid();
     }
     return $result;
 }