private void addJoint(PhysicsJoint joint) {
        if(physicsJoints.containsKey(joint.getObjectId())){
            logger.log(Level.WARNING, "Joint {0} already exists in PhysicsSpace, cannot add.", joint);
            return;
        }
        logger.log(Level.FINE, "Adding Joint {0} to physics space.", joint.getObjectId());
        physicsJoints.put(joint.getObjectId(), joint);
        dynamicsWorld.addConstraint(joint.getObjectId(), !joint.isCollisionBetweenLinkedBodys());
    }
Removes all physics controls and joints in the given spatial from the physics space
(e.g. before saving to disk) - recursive if node
@param spatial the rootnode containing the physics objects
jme3-jbullet/src/main/java/com/jme3/bullet/PhysicsSpace.java