CloseStatus implements Serializable

Closes gh-25507

spring-websocket/src/main/java/org/springframework/web/socket/CloseStatus.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
 
 package org.springframework.web.socket;
 
+import java.io.Serializable;
+
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
@@ -30,7 +32,10 @@ import org.springframework.util.ObjectUtils;
  * @author Rossen Stoyanchev
  * @since 4.0
  */
-public final class CloseStatus {
+public final class CloseStatus implements Serializable {
+
+	private static final long serialVersionUID = 5199057709285570947L;
+
 
 	/**
 	 * "1000 indicates a normal closure, meaning that the purpose for which the connection