订单结果bean实现序列化，使Dubbo RPC等能正常返回结果。

weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/order/WxPayAppOrderResult.java

@@ -3,6 +3,8 @@
 import lombok.Builder;
 import lombok.Data;
 
+import java.io.Serializable;
+
 /**
  * <pre>
  * APP支付调用统一下单接口后的组装所需参数的实现类
@@ -14,7 +16,7 @@
  */
 @Data
 @Builder
-public class WxPayAppOrderResult {
+public class WxPayAppOrderResult implements Serializable {
   private String sign;
   private String prepayId;
   private String partnerId;

weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/order/WxPayMpOrderResult.java

@@ -4,6 +4,8 @@
 import lombok.Builder;
 import lombok.Data;
 
+import java.io.Serializable;
+
 /**
  * <pre>
  * 微信公众号支付进行统一下单后组装所需参数的类
@@ -15,7 +17,7 @@
  */
 @Data
 @Builder
-public class WxPayMpOrderResult {
+public class WxPayMpOrderResult implements Serializable {
   private String appId;
   private String timeStamp;
   private String nonceStr;

weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/order/WxPayMwebOrderResult.java

@@ -2,9 +2,10 @@
 
 import com.thoughtworks.xstream.annotations.XStreamAlias;
 import lombok.AllArgsConstructor;
-import lombok.Builder;
 import lombok.Data;
 
+import java.io.Serializable;
+
 /**
  * <pre>
  * 微信H5支付统一下单后发起支付拼接所需参数实现类.
@@ -15,7 +16,7 @@
  */
 @Data
 @AllArgsConstructor
-public class WxPayMwebOrderResult {
+public class WxPayMwebOrderResult implements Serializable {
   @XStreamAlias("mwebUrl")
   private String mwebUrl;
 }

weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/order/WxPayNativeOrderResult.java

@@ -1,9 +1,10 @@
 package com.github.binarywang.wxpay.bean.order;
 
 import lombok.AllArgsConstructor;
-import lombok.Builder;
 import lombok.Data;
 
+import java.io.Serializable;
+
 /**
  * <pre>
  * 微信扫码支付统一下单后发起支付拼接所需参数实现类
@@ -14,6 +15,6 @@
  */
 @Data
 @AllArgsConstructor
-public class WxPayNativeOrderResult {
+public class WxPayNativeOrderResult implements Serializable {
   private String codeUrl;
 }