public final T invalidate() {
        if (this.valid) {
            this.minSize = minSizeSet ? minSize : null;
            this.prefSize = prefSizeSet ? prefSize : null;
            this.maxSize = maxSizeSet ? maxSize : null;
            if (this.parent != null) parent.invalidate();
            this.valid = false;
        }
        return get();
    }