public function createSubNode($id, $values)
  {
    $result = parent :: createSubNode($id, $values);

    $this->cache->flush(self :: CACHE_GROUP);

    return $result;
  }
 function createSubNode($id, $values)
 {
   $result = parent :: createSubNode($id, $values);
   $this->flushCache();
   return $result;
 }