code: public function restoreDeletedContent($contentId)
      {
          $qb = $this->createQueryBuilder();
          $qb->updateMany()
              ->field('contentId')->equals($contentId)
              ->field('deleted')->set(false)
              ->getQuery()
              ->execute();
      }
docs: @param string $contentId
  
  @throws \Doctrine\ODM\MongoDB\MongoDBException