/**
  * increase container content sequence
  *
  * @param Tinebase_Record_Interface $_record
  * @param string $action
  */
 protected function _increaseContainerContentSequence(Tinebase_Record_Interface $record, $action = NULL)
 {
     parent::_increaseContainerContentSequence($record, $action);
     if ($record->attendee instanceof Tinebase_Record_RecordSet) {
         $updatedContainerIds = array($record->container_id);
         foreach ($record->attendee as $attender) {
             if (isset($attender->displaycontainer_id) && !in_array($attender->displaycontainer_id, $updatedContainerIds)) {
                 Tinebase_Container::getInstance()->increaseContentSequence($attender->displaycontainer_id, $action, $record->getId());
                 $updatedContainerIds[] = $attender->displaycontainer_id;
             }
         }
     }
 }