protected function _toXmlId(Object $pObject, $pXmlNode, $pUseSerializationName, $pDateTimeZone, &$pMainForeignObjects = null)
 {
     $lId = parent::_toXmlId($pObject, $pXmlNode, $pUseSerializationName, $pMainForeignObjects);
     if (is_array($pMainForeignObjects) && !(array_key_exists($this->mModelName, $pMainForeignObjects) && array_key_exists($lId, $pMainForeignObjects[$this->mModelName]))) {
         $lXmlNode = new \SimpleXmlElement("<{$this->getModelName()}/>");
         $this->_toXml($pObject, $lXmlNode, $pUseSerializationName, $pDateTimeZone, $pMainForeignObjects);
         $pMainForeignObjects[$this->mModelName][$lId] = $lXmlNode;
     }
 }