8325361: Make sun.net.www.MessageHeader final

Reviewed-by: dfuchs

src/java.base/share/classes/sun/net/www/MessageHeader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1995, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1995, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -40,17 +40,15 @@
     the header that don't have a valid key, but do have
     a value (this isn't legal according to the standard,
     but lines like this are everywhere). */
-public
-class MessageHeader {
-    private String keys[];
-    private String values[];
+public final class MessageHeader {
+    private String[] keys;
+    private String[] values;
     private int nkeys;
 
     public MessageHeader () {
         grow();
     }
 
-    @SuppressWarnings("this-escape")
     public MessageHeader (InputStream is) throws java.io.IOException {
         parseHeader(is);
     }