code: protected function getBizContent()
      {
          $content = [
              'out_trade_no'  => strval($this->order_no),
              'scene' => $this->scene,
              'auth_code' => $this->auth_code,
              'product_code' => 'FACE_TO_FACE_PAYMENT',
  
              'subject'       => strval($this->subject),
              // TODO 支付宝用户ID
              // 'seller_id' => $this->partner,
  
              'body'          => strval($this->body),
              'total_amount'  => strval($this->amount),
              // TODO 折扣金额
              // 'discountable_amount' => '',
              // TODO  业务扩展参数 订单商品列表信息，待支持
              // 'extend_params => '',
              // 'goods_detail' => '',
  
              'operator_id' => $this->operator_id,
              'store_id' => $this->store_id,
              'terminal_id' => $this->terminal_id,
          ];
  
          $timeExpire = $this->timeout_express;
          if (! empty($timeExpire)) {
              $express = floor(($timeExpire - strtotime($this->timestamp)) / 60);
              ($express > 0) && $content['timeout_express'] = $express . 'm';// 超时时间 统一使用分钟计算
          }
  
          return $content;
      }
docs: 业务请求参数的集合，最大长度不限，除公共参数外所有请求参数都必须放在这个参数中传递
  
  @return string