code: protected function getFindBySubjectQuery()
      {
          if (null !== $this->findBySubjectQuery) {
              return $this->findBySubjectQuery;
          }
  
          $qb = $this->createFindBySubjectQueryBuilder();
  
          return $this->findBySubjectQuery = $qb->getQuery();
      }
docs: Returns the "find by subject" query.
  
  @return \Doctrine\ORM\Query