public Spatial getNodeB() {
        if (nodeB.getUserObject() instanceof Spatial) {
            return (Spatial) nodeB.getUserObject();
        }
        return null;
    }
@return A Spatial if the UserObject of the PhysicsCollisionObject is a Spatial
jme3-jbullet/src/main/java/com/jme3/bullet/collision/PhysicsCollisionEvent.java