code: protected function buildData()
      {
          $signData = [
              // 公共参数
              'version'       => $this->version,
              'charset'       => $this->charset,
              'signType'      => $this->signType,
              'reqData'       => $this->getReqData(),
          ];
  
          // 移除数组中的空值
          $this->retData = ArrayUtil::paraFilter($signData);
      }
docs: 构建数据