class IntegerDifference implements IDifference {

    public static IDifference construct(String name, Integer first, Integer second) {
        if (first == null && second == null) {
            return null; // no difference
        }
        if (first == null || second == null) {
            return new IntegerDifference(name, first, second);
        }
        if (first.intValue() == second.intValue()) {
            return null; // no difference
        }
        return new IntegerDifference(name, first, second);
    }

    private  IntegerDifference(String name, Integer first, Integer second);

}