JScrollPane producing glitches on the screen

I have little experience with Java Swing and am catching up with a simple thing.

The code below produces glitches on the screen when the scroll bar is dragged repeatedly and I do not know why (maximize the screen first to see better and drag the scroll bar up and down).

The example is minimal, complete, and verifiable.

import java.awt.EventQueue;
import java.awt.Font;

import javax.swing.BoxLayout;
import javax.swing.GroupLayout.Alignment;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

public class GroupPanel extends JPanel {

    private static final long serialVersionUID = 1L;

    private JPanel jPanelListaOrders = new JPanel();
    private JScrollPane jScrollPaneOrders = new JScrollPane(jPanelListaOrders);

    public GroupPanel() {

        javax.swing.GroupLayout jPanelMainLayout = new javax.swing.GroupLayout(this);

        jPanelMainLayout.setHorizontalGroup(jPanelMainLayout.createParallelGroup(Alignment.LEADING)
                .addGroup(jPanelMainLayout.createSequentialGroup()
                        .addGroup(jPanelMainLayout.createParallelGroup(Alignment.LEADING)
                                .addComponent(jScrollPaneOrders))
                        ));

        jPanelMainLayout.setVerticalGroup(jPanelMainLayout.createParallelGroup(Alignment.LEADING)
                .addGroup(jPanelMainLayout.createSequentialGroup().addGroup(
                        jPanelMainLayout.createParallelGroup(Alignment.LEADING)
                        .addGroup(jPanelMainLayout.createSequentialGroup()
                                .addComponent(jScrollPaneOrders)))));

        this.setLayout(jPanelMainLayout);

        jPanelListaOrders.setBackground(new java.awt.Color(254, 254, 254));
        jPanelListaOrders.setLayout(new javax.swing.BoxLayout(jPanelListaOrders, javax.swing.BoxLayout.Y_AXIS));

        for (int i = 1; i <= 20; i++) {
            JLabel label = new JLabel("Exemplo " + i);
            label.setFont(new Font("Tahoma", Font.BOLD, 60));
            jPanelListaOrders.add(label);
        }

        revalidate();
        repaint();
    }

    private static void display() {
        JFrame f = new JFrame("GroupPanel");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setLayout(new BoxLayout(f.getContentPane(), BoxLayout.Y_AXIS));
        f.add(new GroupPanel());
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                display();
            }
        });
    }
}

Glitches screen: