private function setMapChilds(SimpleXMLElement $element)
    {
        $nb_map_list = $this->nb_data_object->getChilds();
        if ($nb_map_list->getSize() > 0) {
            $xml_childs = new CNabuXMLSiteMapList($nb_map_list);
            $xml_childs->build($element);
        }
    }