private function findInitialWrongDepthGap()
    {
        // get nodes where difference to parents depth > 1
        $qb = $this->accountRepository->createQueryBuilder('c2')
            ->select('count(c2.id) as results')
            ->join('c2.parent', 'c1')
            ->where('(c2.depth - 1) <> c1.depth');
        $depthGapResult = $qb->getQuery()->getSingleScalarResult();

        return $depthGapResult;
    }