#884 微信公众号模块增加主体变更迁移用户openid的接口

* 增加接口 微信公众号主体变更迁移用户 openid

* add test

weixin-java-mp/src/main/java/me/chanjar/weixin/mp/bean/result/WxMpChangeOpenid.java

@@ -0,0 +1,34 @@
+package me.chanjar.weixin.mp.bean.result;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonObject;
+import com.google.gson.reflect.TypeToken;
+import lombok.Data;
+import me.chanjar.weixin.mp.util.json.WxMpGsonBuilder;
+
+import java.io.Serializable;
+import java.lang.reflect.Type;
+import java.util.List;
+
+/**
+ * 主体变更迁移用户 openid 返回.
+ *
+ * @author 007gzs
+ */
+@Data
+public class WxMpChangeOpenid implements Serializable {
+  private static final long serialVersionUID = -8132023284876534743L;
+  private String oriOpenid;
+  private String newOpenid;
+  private String errMsg;
+  public static WxMpChangeOpenid fromJson(String json) {
+    return WxMpGsonBuilder.create().fromJson(json, WxMpChangeOpenid.class);
+  }
+  public static List<WxMpChangeOpenid> fromJsonList(String json) {
+    Type collectionType = new TypeToken<List<WxMpChangeOpenid>>() {
+    }.getType();
+    Gson gson = WxMpGsonBuilder.create();
+    JsonObject jsonObject = gson.fromJson(json, JsonObject.class);
+    return gson.fromJson(jsonObject.get("result_list"), collectionType);
+  }
+}