@Override
    public int glClientWaitSync(final Object sync, final int flags, final long timeout) {
        return ARBSync.glClientWaitSync((Long) sync, flags, timeout);
    }
The LWJGL implementation og {@link GLExt}.
jme3-lwjgl3/src/main/java/com/jme3/renderer/lwjgl/LwjglGLExt.java