code: public String formatDetailDatas(){
          StringBuilder details = new StringBuilder();
          for (RefundDetailData data : detailDatas){
              details.append(data.format()).append("#");
          }
          details.deleteCharAt(details.length() - 1);
          return details.toString();
      }
docs: 格式化退款数据
  {@link me.hao0.alipay.model.enums.AlipayField#DETAIL_DATA}
  @return 退款数据