class SizeSelectors {

    public static SelectorFunction<Collection<Size>, Size> smallestSize() {
        return new SelectorFunction<Collection<Size>, Size>() {
            @Override
            public Size select(Collection<Size> items) {
                if (items.isEmpty()) {
                    return null;
                }

                return Collections.min(items, COMPARATOR_BY_AREA);
            }
        };
    }

}