🚀 go-pugleaf

How can I make the nodes of a JTree ?
Is there any method ?
Only the root is visible

I've the following
DefaultMutableTreeNode root = new DefaultMutableTreeNode("root");
DefaultMutableTreeNode item1 = new DefaultMutableTreeNode("item1");
DefaultMutableTreeNode item2 = new DefaultMutableTreeNode("item2");
DefaultMutableTreeNode item21 = new DefaultMutableTreeNode("item21");
DefaultMutableTreeNode item22 = new DefaultMutableTreeNode("item22");
root.add(item1);
root.add(item2);
item21.add(item2);
DefaultTreeModel treeModel = new DefaultTreeModel(root);
Jtree jt = new JTree(root);
JScrollPane jsp = new JScrollPane(jt);

I would like to have

  root
   |
   |--item1
   |
   |--item2
        |
        |--item21
        |
        |--item22

Can s.o. help me ?
Thanks in advance.

Rem : I'm using JBuilder 3 enterprise Solaris Edition 3.0.35.1.0