protected function findLastVersionInLanguage(Stage $qa)
    {
        $elementName = 'node';
        $qa->sort(array('createdAt' => 1));
        $qa->group(array(
            '_id' => array('nodeId' => '$nodeId', 'language' => '$language'),
            $elementName => array('$last' => '$$ROOT')
        ));

        return $this->hydrateAggregateQuery($qa, $elementName);
    }
protected function findLastVersionInLanguage(Stage $qa)
    {
        $elementName = 'node';
        $qa->sort(array('createdAt' => 1));
        $qa->group(array(
            '_id' => array('nodeId' => '$nodeId', 'language' => '$language'),
            $elementName => array('$last' => '$$ROOT')
        ));

        return $this->hydrateAggregateQuery($qa, $elementName);
    }
@param Stage $qa

@return array