void invalidateUpdateList() {
        updateListValid = false;
        if (parent != null) {
            parent.invalidateUpdateList();
        }
    }
Called to invalidate the root node's update list.  This is
 called whenever a spatial is attached/detached as well as
 when a control is added/removed from a Spatial in a way
 that would change state.
jme3-core/src/main/java/com/jme3/scene/Node.java