if (state != null) state.setResolver(null);
if (state != null) { State oldState = state; state = null; oldState.setResolver(null); }
	public void setState(State newState) {		// to avoid infinite (mutual) recursion		if (state == newState)			return;		// if it was linked to a previous state, unlink first		if (state != null)			state.setResolver(null);		state = newState;		if (newState != null)			state.setResolver(this);		// forget any dependency state created before		flush();	}