@Override
    public void simpleUpdate(float tpf) {
        if (ghostControl.getOverlappingObjects().contains(collisionNode.getControl(PhysicsControl.class))) {
            fpsText.setText("collide");
        }
    }
Tests attaching ghost nodes to physics nodes via the scene graph
@author normenhansen
jme3-examples/src/main/java/jme3test/bullet/TestAttachGhostObject.java