public function getRootCategoriesPager($page = 1, $limit = 25, $criteria = [])
    {
        $page = 0 === (int) $page ? 1 : (int) $page;

        $queryBuilder = $this->getObjectManager()->createQueryBuilder()
            ->select('c')
            ->from($this->class, 'c')
            ->andWhere('c.parent IS NULL');

        $pager = new Pager($limit);
        $pager->setQuery(new ProxyQuery($queryBuilder));
        $pager->setPage($page);
        $pager->init();

        return $pager;
    }