8300084: AquaFileChooserUI.getDefaultButton returns null

Reviewed-by: aivanov, serb

Author: Tejesh R

src/java.desktop/macosx/classes/com/apple/laf/AquaFileChooserUI.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2023, 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
@@ -593,6 +593,11 @@ protected JButton getApproveButton(final JFileChooser fc) {
         return fApproveButton;
     }
 
+    @Override
+    public JButton getDefaultButton(JFileChooser fc) {
+        return getApproveButton(fc);
+    }
+
     public int getApproveButtonMnemonic(final JFileChooser fc) {
         return fSubPanel.getApproveButtonMnemonic(fc);
     }