protected function buildSortParameter() {
        $sorts = $this->getIndexCriteria()->getSorts();
        if(!empty($sorts)) {
            $orderBy = '';
            foreach($sorts as $sort) {
                $this->buildSortRecursive($this->getEntityFactory(), $sort->getFields(), $sort->isAsc(), $orderBy);
            }
            $this->getCriteria()->orderBy($orderBy);
        }
    }