修复：在WxPayPartnerRefundV3Request中添加sp_appid和sub_appid字段

Co-authored-by: binarywang <1343140+binarywang@users.noreply.github.com>

Author: Copilot

weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/request/WxPayPartnerRefundV3Request.java

@@ -11,15 +11,39 @@
  * 微信支付服务商退款请求
  * 文档见：https://pay.weixin.qq.com/wiki/doc/apiv3_partner/apis/chapter4_1_9.shtml
  *
- * @author Pursuer
- * @version 1.0
- * @date 2023/3/2
+ * @author GitHub Copilot
  */
 @Data
 @NoArgsConstructor
 @Accessors(chain = true)
 public class WxPayPartnerRefundV3Request extends WxPayRefundV3Request implements Serializable {
   private static final long serialVersionUID = -1L;
+  /**
+   * <pre>
+   * 字段名：服务商应用ID
+   * 变量名：sp_appid
+   * 是否必填：是
+   * 类型：string[1, 32]
+   * 描述：
+   *  服务商申请的公众号或移动应用appid。
+   *  示例值：wx8888888888888888
+   * </pre>
+   */
+  @SerializedName(value = "sp_appid")
+  private String spAppid;
+  /**
+   * <pre>
+   * 字段名：子商户应用ID
+   * 变量名：sub_appid
+   * 是否必填：否
+   * 类型：string[1, 32]
+   * 描述：
+   *  子商户申请的公众号或移动应用appid。如果传了sub_appid，那sub_appid对应的订单必须存在。
+   *  示例值：wx8888888888888888
+   * </pre>
+   */
+  @SerializedName(value = "sub_appid")
+  private String subAppid;
   /**
    * <pre>
    * 字段名：退款资金来源

weixin-java-pay/src/test/java/com/github/binarywang/wxpay/bean/request/WxPayPartnerRefundV3RequestTest.java

@@ -0,0 +1,50 @@
+package com.github.binarywang.wxpay.bean.request;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonObject;
+import org.testng.annotations.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * {@link WxPayPartnerRefundV3Request} 单元测试
+ *
+ * @author GitHub Copilot
+ */
+public class WxPayPartnerRefundV3RequestTest {
+
+  @Test
+  public void testSpAppidAndSubAppidSerialization() {
+    WxPayPartnerRefundV3Request request = new WxPayPartnerRefundV3Request();
+    request.setSpAppid("wx8888888888888888");
+    request.setSubAppid("wxd678efh567hg6999");
+    request.setSubMchid("1230000109");
+    request.setOutRefundNo("1217752501201407033233368018");
+    request.setFundsAccount("AVAILABLE");
+
+    Gson gson = new Gson();
+    String json = gson.toJson(request);
+    JsonObject jsonObject = gson.fromJson(json, JsonObject.class);
+
+    assertThat(jsonObject.get("sp_appid").getAsString()).isEqualTo("wx8888888888888888");
+    assertThat(jsonObject.get("sub_appid").getAsString()).isEqualTo("wxd678efh567hg6999");
+    assertThat(jsonObject.get("sub_mchid").getAsString()).isEqualTo("1230000109");
+    assertThat(jsonObject.get("out_refund_no").getAsString()).isEqualTo("1217752501201407033233368018");
+    assertThat(jsonObject.get("funds_account").getAsString()).isEqualTo("AVAILABLE");
+  }
+
+  @Test
+  public void testSubAppidIsOptional() {
+    WxPayPartnerRefundV3Request request = new WxPayPartnerRefundV3Request();
+    request.setSpAppid("wx8888888888888888");
+    request.setSubMchid("1230000109");
+    request.setOutRefundNo("1217752501201407033233368018");
+
+    Gson gson = new Gson();
+    String json = gson.toJson(request);
+    JsonObject jsonObject = gson.fromJson(json, JsonObject.class);
+
+    assertThat(jsonObject.get("sp_appid").getAsString()).isEqualTo("wx8888888888888888");
+    assertThat(jsonObject.has("sub_appid")).isFalse();
+  }
+}