code: private Map<String, String> buildWapPayParams(WapPayDetail wapPayDetail) {
  
          // 公共参数
          Map<String, String> wapPayParams = buildPayParams(wapPayDetail, Service.WAP_PAY);
  
          // WAP特有参数
          putIfNotEmpty(wapPayParams, AlipayField.SHOW_URL, wapPayDetail.getShowUrl());
          putIfNotEmpty(wapPayParams, AlipayField.RN_CHECK, wapPayDetail.getRnCheck());
          putIfNotEmpty(wapPayParams, AlipayField.AIR_TICKET, wapPayDetail.getAirTicket());
          putIfNotEmpty(wapPayParams, AlipayField.BUYER_CERT_NO, wapPayDetail.getBuyerCertNo());
          putIfNotEmpty(wapPayParams, AlipayField.BUYER_REAL_NAME, wapPayDetail.getBuyerRealName());
          putIfNotEmpty(wapPayParams, AlipayField.EXTERN_TOKEN, wapPayDetail.getExternToken());
          putIfNotEmpty(wapPayParams, AlipayField.OTHER_FEE, wapPayDetail.getOtherFee());
          putIfNotEmpty(wapPayParams, AlipayField.SCENE, wapPayDetail.getScene());
  
          // md5签名参数
          buildMd5SignParams(wapPayParams);
  
          return wapPayParams;
      }
docs: 构建WAP支付参数
  @param wapPayDetail 字段集合
  @return WAP支付参数