JTableの水平JScrollBarをリサイズ可能にするためJSplitPaneに再配置する

DefaultTableModel m1 = new DefaultTableModel(100, 256);
JTable table = new JTable(m1);
table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
JScrollPane scroll = new JScrollPane(table);
scroll.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);

JPanel panel = new JPanel(new BorderLayout());
panel.setOpaque(false);
panel.setBorder(BorderFactory.createEmptyBorder(3, 0, 0, 0));
panel.add(scroll.getHorizontalScrollBar());

JSplitPane horizontalBox = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT);
horizontalBox.setBackground(Color.WHITE);
horizontalBox.setLeftComponent(box);
horizontalBox.setRightComponent(panel);
horizontalBox.setContinuousLayout(true);
horizontalBox.setBorder(BorderFactory.createEmptyBorder());
EventQueue.invokeLater(() -> horizontalBox.setDividerLocation(.4));

JLabel tripleColon = new JLabel("⫶");
tripleColon.setForeground(Color.GRAY);
tripleColon.setBorder(BorderFactory.createEmptyBorder(3, 0, 0, 0));

BasicSplitPaneDivider divider = ((BasicSplitPaneUI) horizontalBox.getUI()).getDivider();
divider.setLayout(new BorderLayout());
divider.setBorder(BorderFactory.createEmptyBorder());
divider.setBackground(Color.WHITE);
divider.add(tripleColon);
divider.setDividerSize(8);