public function getMaxChildrenWeight(Node $parentNode = null, $lang = null)
    {
        $maxWeight = $this->getNodeTranslationsQueryBuilder($lang)
            ->select('max(nt.weight)')
            ->andWhere('n.parent = :parentNode')
            ->setParameter('parentNode', $parentNode)
            ->getQuery()
            ->getSingleScalarResult();

        return (int) $maxWeight;
    }