@Override
            public void internalTick(DynamicsWorld dw, float f) {
                for (Iterator<PhysicsTickListener> it = tickListeners.iterator(); it.hasNext();) {
                    PhysicsTickListener physicsTickCallback = it.next();
                    physicsTickCallback.physicsTick(space, f);
                }
            }
Has to be called from the (designated) physics thread
jme3-jbullet/src/main/java/com/jme3/bullet/PhysicsSpace.java