@Override
    public void read(JmeImporter im) throws IOException {
        InputCapsule capsule = im.getCapsule(this);
        this.nodeA = ((PhysicsRigidBody) capsule.readSavable("nodeA", null));
        this.nodeB = (PhysicsRigidBody) capsule.readSavable("nodeB", null);
        this.pivotA = (Vector3f) capsule.readSavable("pivotA", new Vector3f());
        this.pivotB = (Vector3f) capsule.readSavable("pivotB", new Vector3f());
    }
destroys this joint and removes it from its connected PhysicsRigidBody's joint lists
jme3-jbullet/src/main/java/com/jme3/bullet/joints/PhysicsJoint.java