public function findAllIterator($configurationHash = null)
    {
        /** @var QueryBuilder $queryBuilder */
        $queryBuilder = $this->entityManager->createQueryBuilder();
        $queryBuilder
            ->select('t')
            ->from($this->getEntityClassName(), 't');
        if ($configurationHash !== null) {
            $queryBuilder
                ->where('t.configurationHash = :configurationHash')
                ->setParameter('configurationHash', $configurationHash);
        }
        return $queryBuilder->getQuery()->iterate();
    }