@Override
    public void write(JmeExporter e) throws IOException {
        OutputCapsule capsule = e.getCapsule(this);
        capsule.write(collisionGroup, "collisionGroup", 0x00000001);
        capsule.write(collisionGroupsMask, "collisionGroupsMask", 0x00000001);
        capsule.write(collisionShape, "collisionShape", null);
    }
@param userObject the userObject to set
jme3-jbullet/src/main/java/com/jme3/bullet/collision/PhysicsCollisionObject.java