Method uniqify

src/main/java/fieldbox/io/IO.java:156–185

(Box x)

		ArrayList<Dict.Prop> k = new ArrayList<>(x.properties.getMap()
			.keySet());

		List<Runnable> undo = new LinkedList<>();

		for (Dict.Prop kk : k) {
			if (kk.getName()
				.startsWith("__filename__") || kk.getName()
				.startsWith("__datafilename__")) {
				Object was = x.properties.remove(kk);
				undo.add(() -> {
					x.properties.put(kk, was);
				});
			}
		}

		if (x.properties.has(IO.id)) {
			String was = x.properties.remove(IO.id);
			undo.add(() -> {
				x.properties.put(IO.id, was);
			});
			x.properties.put(IO.id, Box.newID());
		} else
			x.properties.put(IO.id, Box.newID());

		return () -> {
			for (Runnable u : undo) u.run();
		};
	}


	public static boolean uniqifyIfNecessary(Box root, Box x) {

		String id = x.properties.computeIfAbsent(IO.id, k -> Box.newID());