@Override
    public void write(JmeExporter ex) throws IOException {
        super.write(ex);
        OutputCapsule capsule = ex.getCapsule(this);
        capsule.write(halfExtents, "halfExtents", new Vector3f(1, 1, 1));
    }
creates a collision box from the given halfExtents
@param halfExtents the halfExtents of the CollisionBox
jme3-jbullet/src/main/java/com/jme3/bullet/collision/shapes/BoxCollisionShape.java