docs: public static MchPayApp generateMchAppData(String prepay_id, String appId, String partnerid, String key) {
  		Map<String, String> wx_map = new LinkedHashMap<String, String>();
  		wx_map.put("appid", appId);
  		wx_map.put("partnerid", partnerid);
  		wx_map.put("prepayid", prepay_id);
  		wx_map.put("package", "Sign=WXPay");
  		wx_map.put("noncestr", UUID.randomUUID().toString().replace("-", ""));
  		wx_map.put("timestamp", System.currentTimeMillis() / 1000 + "");
  		String sign = SignatureUtil.generateSign(wx_map, key);
  		MchPayApp mchPayApp = new MchPayApp();
  		mchPayApp.setAppid(appId);
  		mchPayApp.setPartnerid(partnerid);
  		mchPayApp.setPrepayid(prepay_id);
  		mchPayApp.setPackage_(wx_map.get("package"));
  		mchPayApp.setNoncestr(wx_map.get("noncestr"));
  		mchPayApp.setTimestamp(wx_map.get("timestamp"));
  		mchPayApp.setSign(sign);
  		return mchPayApp;
  	}