public function unify(array $params)
    {
        if (empty($params['spbill_create_ip'])) {
            $params['spbill_create_ip'] = ('NATIVE' === $params['trade_type']) ? Support\get_server_ip() : Support\get_client_ip();
        }

        $params['appid'] = $this->app['config']->app_id;
        $params['notify_url'] = $params['notify_url'] ?? $this->app['config']['notify_url'];

        return $this->request($this->wrap('pay/unifiedorder'), $params);
    }