@Override
public void treeCollapsed(TreeExpansionEvent event) {
DefaultMutableTreeNode node = (DefaultMutableTreeNode) event.getPath().getLastPathComponent();
@SuppressWarnings("unchecked")
Enumeration<DefaultMutableTreeNode> children = node.children();
while (children.hasMoreElements()) {
DefaultMutableTreeNode child = children.nextElement();
System.out.println("removing children of " + ((NodeInfo) child.getUserObject()).getFullName());
child.removeAllChildren();
}