public function getDescendantsContentUids($contents)
    {
        if (false === is_array($contents)) {
            $contents = array($contents);
        }

        $meta = $this->_em->getClassMetadata('BackBee\ClassContent\Indexes\IdxContentContent');

        $q = $this->_em->getConnection()
                ->createQueryBuilder()
                ->select('c.'.$meta->getColumnName('subcontent_uid'))
                ->from($meta->getTableName(), 'c');

        $index = 0;
        $atleastone = false;
        foreach ($contents as $content) {
            if (false === ($content instanceof AbstractClassContent)) {
                continue;
            }

            if (true === $content->isElementContent()) {
                continue;
            }

            $q->orWhere('c.'.$meta->getColumnName('content_uid').' = :uid'.$index)
                    ->setParameter('uid'.$index, $content->getUid());

            $index++;
            $atleastone = true;
        }

        return (true === $atleastone) ? array_unique($q->execute()->fetchAll(\PDO::FETCH_COLUMN)) : array();
    }