code: public function apply(array $options = [])
      {
          $payRequest = [
              'appId'     => $this->userConfig->get('app_id'),
              'timeStamp' => time() . '',
              'nonceStr'  => $this->createNonceStr(),
              'package'   => 'prepay_id=' . $this->preOrder($options)['prepay_id'],
              'signType'  => 'MD5',
          ];
          $payRequest['paySign'] = $this->getSign($payRequest);
          return $payRequest;
      }
docs: 设置并返回参数
  @param array $options
  @return array
  @throws \Pay\Exceptions\GatewayException