public function findOneForHubIdAndStartTime($hub_id, $start_time)
    {
        $qb = $this->getEntityManager()->createQueryBuilder()
            ->from('HarvestCloudCoreBundle:SellerWindow', 'pw')
            ->select('pw')
            ->where('pw.start_time = :start_time')
            ->andWhere('pw.start_time > :now')
            ->setParameter('start_time', date('Y-m-d H:i:s', $start_time))
            ->setParameter('now', date('Y-m-d H:i:s'))
        ;

        $q = $qb->getQuery();

        return $q->getOneOrNullResult();
    }