A DESCRIPTION OF THE PROBLEM :
The problem started appearing after upgrading from Java 21 to 25.

With Java 21, my menus looked like this :

<LINK>

With Java 25, a gutter started appearing :

<LINK>


REGRESSION : Last worked in version 21.0.9

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Use the following example

// Source - <LINK>

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ButtonGroup;
import javax.swing.ImageIcon;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.WindowConstants;

public class IconMenuExample {

    public static void main(String[] args) throws Exception {

        // we set the Windows Look And Feel
        UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");

        SwingUtilities.invokeLater(() -> {

            JFrame frame = new JFrame("Menu Icon Example");

            JMenuBar menuBar = new JMenuBar();
            JMenu fileMenu = new JMenu("File");

            // we create sample actions using programmatic sixteen by sixteen ImageIcon instances
            Action openAction = newAction(
                    "Open",
                    createColorIcon(Color.BLUE),
                    e -> System.out.println("Open")
            );

            Action saveAction = newAction(
                    "Save",
                    createColorIcon(Color.GREEN),
                    e -> System.out.println("Save")
            );

            Action exitAction = newAction(
                    "Exit",
                    createColorIcon(Color.RED),
                    e -> System.exit(0)
            );

            // we attach the actions to menu items
            fileMenu.add(new JMenuItem(openAction));
            fileMenu.add(new JMenuItem(saveAction));
            fileMenu.addSeparator();
            fileMenu.add(new JMenuItem(exitAction));

            // we create the second menu with check box menu items
            JMenu optionsMenu = new JMenu("Options");

            JCheckBoxMenuItem checkOne = new JCheckBoxMenuItem("Enable Feature One");
            checkOne.addActionListener(e -> System.out.println("Feature One toggled: " + checkOne.isSelected()));

            JCheckBoxMenuItem checkTwo = new JCheckBoxMenuItem("Enable Feature Two");
            checkTwo.addActionListener(e -> System.out.println("Feature Two toggled: " + checkTwo.isSelected()));

            optionsMenu.add(checkOne);
            optionsMenu.add(checkTwo);

            // we create the third menu with radio button menu items
            JMenu modeMenu = new JMenu("Mode");

            JRadioButtonMenuItem modeA = new JRadioButtonMenuItem("Mode A");
            JRadioButtonMenuItem modeB = new JRadioButtonMenuItem("Mode B");
            JRadioButtonMenuItem modeC = new JRadioButtonMenuItem("Mode C");

            ButtonGroup modeGroup = new ButtonGroup();
            modeGroup.add(modeA);
            modeGroup.add(modeB);
            modeGroup.add(modeC);

            modeA.setSelected(true);

            modeA.addActionListener(e -> System.out.println("Mode A selected"));
            modeB.addActionListener(e -> System.out.println("Mode B selected"));
            modeC.addActionListener(e -> System.out.println("Mode C selected"));

            modeMenu.add(modeA);
            modeMenu.add(modeB);
            modeMenu.add(modeC);

            // we add all menus to the bar
            menuBar.add(fileMenu);
            menuBar.add(optionsMenu);
            menuBar.add(modeMenu);

            frame.setJMenuBar(menuBar);

            frame.setSize(300, 200);
            frame.setLocationRelativeTo(null);
            frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
            frame.setVisible(true);
        });
    }

    public static Action newAction(String name, ImageIcon icon, ActionListener listener) {
        Action action = new AbstractAction(name) {
            @Override
            public void actionPerformed(ActionEvent e) {
                listener.actionPerformed(e);
            }
        };
        action.putValue(Action.SMALL_ICON, icon);
        return action;
    }

    // we create a programmatic sixteen by sixteen ImageIcon filled with the given color
    private static ImageIcon createColorIcon(Color color) {
        int size = 16;
        BufferedImage image = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g = image.createGraphics();
        try {
            g.setColor(color);
            g.fillRect(0, 0, size, size);
        } finally {
            g.dispose();
        }
        return new ImageIcon(image);
    }
}


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Expected no left gutter when no checkbox/radio
ACTUAL -
Visible left gutter when no checkbox/radio

---------- BEGIN SOURCE ----------
Use the following example

// Source - <LINK>
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ButtonGroup;
import javax.swing.ImageIcon;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.WindowConstants;

public class IconMenuExample {

    public static void main(String[] args) throws Exception {

        // we set the Windows Look And Feel
        UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");

        SwingUtilities.invokeLater(() -> {

            JFrame frame = new JFrame("Menu Icon Example");

            JMenuBar menuBar = new JMenuBar();
            JMenu fileMenu = new JMenu("File");

            // we create sample actions using programmatic sixteen by sixteen ImageIcon instances
            Action openAction = newAction(
                    "Open",
                    createColorIcon(Color.BLUE),
                    e -> System.out.println("Open")
            );

            Action saveAction = newAction(
                    "Save",
                    createColorIcon(Color.GREEN),
                    e -> System.out.println("Save")
            );

            Action exitAction = newAction(
                    "Exit",
                    createColorIcon(Color.RED),
                    e -> System.exit(0)
            );

            // we attach the actions to menu items
            fileMenu.add(new JMenuItem(openAction));
            fileMenu.add(new JMenuItem(saveAction));
            fileMenu.addSeparator();
            fileMenu.add(new JMenuItem(exitAction));

            // we create the second menu with check box menu items
            JMenu optionsMenu = new JMenu("Options");

            JCheckBoxMenuItem checkOne = new JCheckBoxMenuItem("Enable Feature One");
            checkOne.addActionListener(e -> System.out.println("Feature One toggled: " + checkOne.isSelected()));

            JCheckBoxMenuItem checkTwo = new JCheckBoxMenuItem("Enable Feature Two");
            checkTwo.addActionListener(e -> System.out.println("Feature Two toggled: " + checkTwo.isSelected()));

            optionsMenu.add(checkOne);
            optionsMenu.add(checkTwo);

            // we create the third menu with radio button menu items
            JMenu modeMenu = new JMenu("Mode");

            JRadioButtonMenuItem modeA = new JRadioButtonMenuItem("Mode A");
            JRadioButtonMenuItem modeB = new JRadioButtonMenuItem("Mode B");
            JRadioButtonMenuItem modeC = new JRadioButtonMenuItem("Mode C");

            ButtonGroup modeGroup = new ButtonGroup();
            modeGroup.add(modeA);
            modeGroup.add(modeB);
            modeGroup.add(modeC);

            modeA.setSelected(true);

            modeA.addActionListener(e -> System.out.println("Mode A selected"));
            modeB.addActionListener(e -> System.out.println("Mode B selected"));
            modeC.addActionListener(e -> System.out.println("Mode C selected"));

            modeMenu.add(modeA);
            modeMenu.add(modeB);
            modeMenu.add(modeC);

            // we add all menus to the bar
            menuBar.add(fileMenu);
            menuBar.add(optionsMenu);
            menuBar.add(modeMenu);

            frame.setJMenuBar(menuBar);

            frame.setSize(300, 200);
            frame.setLocationRelativeTo(null);
            frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
            frame.setVisible(true);
        });
    }

    public static Action newAction(String name, ImageIcon icon, ActionListener listener) {
        Action action = new AbstractAction(name) {
            @Override
            public void actionPerformed(ActionEvent e) {
                listener.actionPerformed(e);
            }
        };
        action.putValue(Action.SMALL_ICON, icon);
        return action;
    }

    // we create a programmatic sixteen by sixteen ImageIcon filled with the given color
    private static ImageIcon createColorIcon(Color color) {
        int size = 16;
        BufferedImage image = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g = image.createGraphics();
        try {
            g.setColor(color);
            g.fillRect(0, 0, size, size);
        } finally {
            g.dispose();
        }
        return new ImageIcon(image);
    }
}

---------- END SOURCE ----------