DoctrineExtensions\Query\MysqlWalker::walkGroupByClause PHP Method

    public function walkGroupByClause($groupByClause)
    {
        $sql = parent::walkGroupByClause($groupByClause);
        // Gets the query
        $query = $this->getQuery();
        if ($query->getHint('mysqlWalker.withRollup') === true) {
            // Appends the WITH ROLLUP modifier
            $sql .= ' WITH ROLLUP';
        }
        return $sql;
    }