/**
     * @param int $groupId
     * @param int $entityId
     */
    public function dropReferenceDataByGroupAndEntityId($groupId, $entityId) {

        $rsm = new ResultSetMappingBuilder($this->getEntityManager());
        $rsm->addRootEntityFromClassMetadata('AppBundle:ReferenceData', 'rd');

        $this
            ->getEntityManager()
            ->createNativeQuery(
                ' DELETE FROM ' . $this->getMappingTableName() .
                ' WHERE '.
                  ' group_id = :groupId AND ' .
                  $this->getEntityIdColumnName() .' = :entityId ', $rsm)
            ->setParameter('groupId', $groupId)
            ->setParameter('entityId', $entityId)
            ->execute();
    }