public function removeNotification(OW_Event $event)
 {
     $params = $event->getParams();
     if (empty($params['entityType']) || empty($params['entityId'])) {
         throw new InvalidArgumentException('`entityType` and `entityId` params are required');
     }
     $userId = empty($params['userId']) ? null : $params['userId'];
     $entityType = $params['entityType'];
     $entityId = $params['entityId'];
     if ($userId !== null) {
         $this->service->deleteNotification($entityType, $entityId, $userId);
     } else {
         $this->service->deleteNotificationByEntity($entityType, $entityId);
     }
 }