@Override
    public int compareTo(DateTimeStamp dateTimeStamp) {
        return  comparator.compare(this,dateTimeStamp);
    }
@Test
    void testCompareLessThan() {
        DateTimeStamp smaller = new DateTimeStamp("2018-04-04T09:10:00.586-0100");
        DateTimeStamp greater = new DateTimeStamp("2018-04-04T10:10:00.587-0100");
        assertEquals(-1, smaller.compareTo(greater));
    }