JSplitPaneのDivider位置を推奨サイズでリセットする

SpinnerNumberModel model1 = new SpinnerNumberModel(100, 10, 300, 10);
JScrollPane scroll1 = makeScrollPane(new JTree(), model1);
SpinnerNumberModel model2 = new SpinnerNumberModel(150, 10, 300, 10);
JTextArea textArea = new JTextArea();
JScrollPane scroll2 = makeScrollPane(textArea, model2);
JSplitPane split = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, scroll1, scroll2);
split.setOneTouchExpandable(true);
split.setContinuousLayout(true);
JMenu menu1 = new JMenu("JSplitPane");
menu1.add(makeSpinner("L: ", model1));
menu1.add(makeSpinner("R: ", model2));
menu1.addSeparator();
menu1.add("resetToPreferredSizes").addActionListener(e -> {
  split.resetToPreferredSizes();
  info(split, textArea);
});
menu1.addSeparator();
// ...
JMenu menu2 = new JMenu("ResizeWeight");
JRadioButtonMenuItem r0 = new JRadioButtonMenuItem("0.0", true);
menu2.add(r0).addActionListener(e -> split.setResizeWeight(0d));
JRadioButtonMenuItem r1 = new JRadioButtonMenuItem("0.5");
menu2.add(r1).addActionListener(e -> split.setResizeWeight(.5));
JRadioButtonMenuItem r2 = new JRadioButtonMenuItem("1.0");
menu2.add(r2).addActionListener(e -> split.setResizeWeight(1d));
ButtonGroup group = new ButtonGroup();
for (AbstractButton r : Arrays.asList(r0, r1, r2)) {
  group.add(r);
}
JMenuBar menuBar = new JMenuBar();
menuBar.add(menu1);
menuBar.add(menu2);