scroll bar appears but content won't wrap vertically

I have a JPanel that I want to dynamically fill with other jpanels, Like this: result If I use a gridLayout it works unless it's not filled, in which case it will stretch the panels inside, like this gridlayout, stretched If I use GridBagLayout it doesn't stretch them when there's few of them, but then it will not scroll when the panel is filled, like this gridbag, noscroll I just can't get it to do both things: only vertical scroll AND no stretching when the panel is not filled. The blue squares are JPanels with a borderLayout that I create passing labels and color as parameters. I tried making them absoluteLayout, gridBagLayout, fix their size, but the JPanel I add them to seems to overrule their settings.

public class Gbmapper extends JFrame {


/**
 * Create the frame.
 */

public Gbmapper() {

    //main window
    setTitle("Gbmapper");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 800, 600);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(null);

    JPanel panelParagrafi = new JPanel(new BorderLayout(4, 4));
    panelParagrafi.setBounds(10, 67, 760, 180);
    panelParagrafi.setBorder(new TitledBorder("Paragrafi"));

    // here's the problem
    JPanel listaNodi = new JPanel(new GridLayout(0,20,2,2));
    //JPanel listaNodi = new JPanel(new GridBagLayout());
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.insets = new Insets(2,2,2,2);
    
    /* flowlayout also will display a single row
    JPanel listaNodi = new JPanel();
    listaNodi.setBounds(10, 67, 764, 180);
    listaNodi.setLayout(new FlowLayout(FlowLayout.CENTER, 5, 5)); */
    
    // init the jpanel with some items
    for (int i = 0; i < 10; i++) {
        // for use with gridlayout
        listaNodi.add( new GbmParNode(Integer.toString(50), Integer.toString(i), 'b')  );
        // for use with gridbaglayout, passes insets
        //listaNodi.add( new GbmParNode(Integer.toString(50), Integer.toString(i), 'b'), gbc  );
        }

    JScrollPane scrollPane = new JScrollPane(listaNodi,
            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
            JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
    
    panelParagrafi.add(scrollPane);
    
    contentPane.add(panelParagrafi);

}} 

// My JPanel class

package gbmapper;

import javax.swing.JPanel;
import javax.swing.JLabel;
import java.awt.Font;
import java.awt.Color;
import java.awt.FlowLayout;
import javax.swing.SwingConstants;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.BorderLayout;

public class GbmParNode extends JPanel {
    
    // COLORI
    Color myGreen = new Color(173, 255, 47);
    Color myRed = new Color(255, 80, 50);
    Color myBlue = new Color(0, 204, 255);
    Color myYellow = new Color(255, 255, 0);
    Color myWhite = new Color(255, 255, 255);
    
    JLabel lblParNum; // = new JLabel(parNum);

    /**
     * Create the panel.
     */

    public GbmParNode(String parNum, String parDesc, char parColor) {
        addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {

            }
        });
            
        Color myColor;

        switch(parColor) {
          case 'g':
            myColor = myGreen;
            break;
          case 'r':
            myColor = myRed;
            break;
          case 'b':
            myColor = myBlue;
            break;
          case 'y':
            myColor = myYellow;
            break;
          default:
            myColor = myWhite;
        }
            
        setBackground(myColor);
        setLayout(new BorderLayout(0, 0));
        //setLayout(new GridBagLayout());
        //setSize(50,50);
        
        lblParNum = new JLabel(parNum);
        lblParNum.setHorizontalAlignment(SwingConstants.CENTER);
        lblParNum.setFont(new Font("Tahoma", Font.PLAIN, 18));
        //lblParNum.setBounds(14, 5, 100, 22);
        add(lblParNum, BorderLayout.CENTER);
        
        JLabel lblParDesc = new JLabel(parDesc);
        lblParDesc.setHorizontalAlignment(SwingConstants.CENTER);
        //lblParDesc.setBounds(14, 25, 100, 14);
        add(lblParDesc, BorderLayout.SOUTH);
    


    }
}