code: public WePayOrder queryByOutTradeNo(String outTradeNo){
          checkNotNullAndEmpty(outTradeNo, "outTradeNo");
          Map<String, String> queryParams = new TreeMap<>();
          put(queryParams, WepayField.OUT_TRADE_NO, outTradeNo);
          return doQueryOrder(queryParams);
      }
docs: 根据商户订单号查询订单
  @param outTradeNo 商户订单号
  @return PayOrder对象，或抛WepayException