public function getSingleTopicQuery($id, $locale = null)
{
$meta = $this->getClassMetadata();
$config = $this->listener->getConfiguration($this->_em, $meta->name);
$queryBuilder = $this->getQueryBuilder()->select('t')->from($config['useObjectClass'], 't')->where('t.id = :id')->setParameter('id', $id);
$query = $queryBuilder->getQuery();
return $this->setTranslatableHint($query, $locale);
}