private void normalize() {
        Set<String> newDeleted = new HashSet<>();
        newDeleted.addAll(deleted.get());

        for (String key : old.keySet()) {
            if (old.get(key).equals(diff.get().get(key))) {
                diff.get().remove(key);
            }
            if (newDeleted.contains(key)) {
                newDeleted.remove(key);
            }
        }

        for (String key : deleted.get()) {
            if (diff.get().containsKey(key)) {
                diff.get().remove(key);
            }
        }

        for (String key : newDeleted) {
            deleted.get().remove(key);
        }
    }