public static function generateXMLTree(SimpleXMLElement $xml)
 {
     $reportBaseClosure = new self();
     $reportBaseClosureIterator = $reportBaseClosure->getAllTopLevelRoots();
     foreach ($reportBaseClosureIterator as $reportBase) {
         $item = $xml->addChild('row');
         $item->addAttribute('id', $reportBase->reportBaseId);
         $item->addChild('cell', $reportBase->displayName);
         $item->addChild('cell', $reportBase->systemName);
         self::_generateTree($item, $reportBase->reportBaseId);
     }
     return $xml;
 }