--- old/src/java.desktop/share/classes/java/awt/event/WindowAdapter.java	2020-08-05 16:55:52.200026700 -0700
+++ new/src/java.desktop/share/classes/java/awt/event/WindowAdapter.java	2020-08-05 16:55:51.625899400 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2020, 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
@@ -56,6 +56,11 @@
     implements WindowListener, WindowStateListener, WindowFocusListener
 {
     /**
+     * Constructs a {@code WindowAdapter}.
+     */
+    protected WindowAdapter() {}
+
+    /**
      * Invoked when a window has been opened.
      */
     public void windowOpened(WindowEvent e) {}