if (getCallback() == null) { setCallback(new PageCallback(ListParkOrbits.PAGE)); }
    public void pageBeginRender(PageEvent event_) {        ParkOrbit orbit = getParkOrbit();        if (null != orbit) {            return;        }        Integer id = getParkOrbitId();        if (null != id) {            CallGroupContext context = getCallGroupContext();            orbit = context.loadParkOrbit(id);        } else {            orbit = new ParkOrbit();        }        setParkOrbit(orbit);    }