s2 = new SimpleTimePeriod(new Date(10L), new Date(20L));
        assertEquals(-1, s1.compareTo(s2));

        s1 = new SimpleTimePeriod(new Date(11L), new Date(21));
        s2 = new SimpleTimePeriod(new Date(10L), new Date(20L));
        assertEquals(1, s1.compareTo(s2));

        s1 = new SimpleTimePeriod(new Date(10L), new Date(18));