@Override   
    public void cloneFields( Cloner cloner, Object original ) { 
        this.spatial = cloner.clone(spatial);
    }
Callback from {@link com.jme3.util.clone.Cloner} to convert this
shallow-cloned control into a deep-cloned one, using the specified cloner
and original to resolve copied fields.

@param cloner the cloner that's cloning this control (not null)
@param original the control from which this control was shallow-cloned
(unused)
jme3-jbullet/src/main/java/com/jme3/bullet/control/GhostControl.java