I have a node with a label node attached. How do I have them act as if they were one single node when users expand or collapse a tree branch?

// my code snippet
ShapeNode node = new ShapeNode(diagram);
node.setExpandable(true);
ShapeNode label = new ShapeNode(diagram);
label.attachTo(node, AttachToNode.TopCenter);
diagram.add(node);
diagram.add(label);
node.getSubordinateGroup().setAutoDeleteItems(true);
node.getSubordinateGroup().setExpandable(true);

Without the node.getSubordinateGroup().setExpandable(true) call above, the child node's label gets left behind (still shown) on a collapse. With this call, labels of both the child and parent nodes are taken away (not shown) on a collapse. Neither gives me the behavior I want.