code: public function findWithUseReferences($siteId)
      {
          $where = "function() { return this.useReferences && Object.keys(this.useReferences).length > 0; }";
          $qb = $this->createQueryBuilder();
          $qb->field('siteId')->equals($siteId)
             ->field('useReferences')->where($where);
  
          return $qb->getQuery()->execute();
      }
docs: @param $siteId
  
  @return Collection
  
  @throws \Doctrine\ODM\MongoDB\MongoDBException