Intento mostrar gráficos en JGraphx. Todo está bien siempre que use Gráficos dirigidos, pero cuando trato de mostrar uno no dirigido, se muestra con dirección.

El código es de la demostración de jgrapht.

package org.jgrapht.demo;

import com.mxgraph.layout.*;
import com.mxgraph.swing.*;

import java.awt.*;
import java.nio.file.FileSystem;

import javax.swing.*;

import org.jgrapht.*;
import org.jgrapht.ext.*;
import org.jgrapht.graph.*;


/**
 * A demo applet that shows how to use JGraphX to visualize JGraphT graphs.
 * Applet based on JGraphAdapterDemo.
 *
 * @since July 9, 2013
 */
public class JGraphXAdapterDemo
    extends JApplet
{


private static final long serialVersionUID = 2202072534703043194L;
private static final Dimension DEFAULT_SIZE = new Dimension(530, 320);



private JGraphXAdapter<String, DefaultEdge> jgxAdapter;



/**
 * An alternative starting point for this demo, to also allow running this
 * applet as an application.
 *
 * @param args ignored.
 */
public static void main(String [] args)
{
    JGraphAdapterDemo applet = new JGraphAdapterDemo();
    applet.init();

    JFrame frame = new JFrame();
    frame.getContentPane().add(applet);
    frame.setTitle("JGraphT Adapter to JGraph Demo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
}

/**
 * {@inheritDoc}
 */
public void init()
{
    // create a JGraphT graph
    ListenableUndirectedGraph<String, DefaultEdge> g =
        new ListenableUndirectedGraph<String, DefaultEdge>(
            DefaultEdge.class);

    // create a visualization using JGraph, via an adapter
    jgxAdapter = new JGraphXAdapter<String, DefaultEdge>(g);

    getContentPane().add(new mxGraphComponent(jgxAdapter));
    resize(DEFAULT_SIZE);

    String v1 = "v1";
    String v2 = "v2";
    String v3 = "v3";
    String v4 = "v4";

    // add some sample data (graph manipulated via JGraphX)
    g.addVertex(v1);
    g.addVertex(v2);
    g.addVertex(v3);
    g.addVertex(v4);

    g.addEdge(v1, v2);
    g.addEdge(v2, v3);
    g.addEdge(v3, v1);
    g.addEdge(v4, v3);

    // positioning via jgraphx layouts
    mxCircleLayout layout = new mxCircleLayout(jgxAdapter);
    layout.execute(jgxAdapter.getDefaultParent());

    // that's all there is to it!...

   }
}

¿Es posible mostrarlo sin dirección?

Gracias

Torben

PD .: Perdón por mi mal inglés