code: public BillDetail<RefundBill> queryRefund(String deviceInfo, String date){
          String data = query(deviceInfo, date, BillType.REFUND);
          return renderBillDetail(data, BillFields.REFUND, RefundBill.class);
      }
docs: 查询退款账单
  @param deviceInfo 微信支付分配的终端设备号，填写此字段，只下载该设备号的对账单
  @param date 账单的日期
  @return 账单明细