@Override
    public void read(JmeImporter im) throws IOException {
        super.read(im);
        InputCapsule capsule = im.getCapsule(this);
        Vector3f halfExtents = (Vector3f) capsule.readSavable("halfExtents", new Vector3f(1, 1, 1));
        this.halfExtents = halfExtents;
        createShape();
    }
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