Doctrine\ODM\MongoDB\Query\Builder::references PHP Method

    public function references($document)
    {
        $this->expr->references($document);
        return $this;
    }

 /**
  * Adds a condition to a the query where the supplied object should exist in the associated
  * collection represented by a field.
  *
  * ##Example:
  *
  *	{{{
  *		$kris = new Person('Kris');
  *		$jon = new Person('Jon');
  *		$kris->save();
  *		$jon->save();
  *		// ... after flush ...
  *		$jon->bestFriend = $kris;
  *		$qb = $person->getDataSource()->createQueryBuilder('Person');
  *		$qb->field('bestFriend')->references($kris);
  *
  *		// You should expect this
  *		$jon === $qb->getSingleResult();
  *	}}}
  *
  * @param object $document instance of any document to be used as reference for the collection
  * @return QueryProxy this instance
  */
 public function references($document)
 {
     $this->queryChanged = true;
     return parent::references($document);
 }