public function toOptionArray()
    {
        return [
            ['value' => BucketInterface::SORT_ORDER_COUNT, 'label' => __('Result count')],
            ['value' => BucketInterface::SORT_ORDER_MANUAL, 'label' => __('Admin sort')],
            ['value' => BucketInterface::SORT_ORDER_TERM, 'label' => __('Name')],
            ['value' => BucketInterface::SORT_ORDER_RELEVANCE, 'label' => __('Relevance')],
        ];
    }