/**
  * Creates embedded message path composed of ancestor messages
  * seperated by slash "/". If message has no ancestor returns empty string.
  *
  * @param DescriptorInterface $descriptor message descriptor
  *
  * @return string
  */
 private function _createEmbeddedMessagePath(DescriptorInterface $descriptor)
 {
     $containing = $descriptor->getContaining();
     $path = array();
     while ($containing) {
         $path[] = $containing->getName();
         $containing = $containing->getContaining();
     }
     array_reverse($path);
     return implode("/", $path);
 }