public Calendar ceil(long t) {
        Calendar cal = new GregorianCalendar(Locale.US);
        cal.setTimeInMillis(t);
        return ceil(cal);
    }
@Test
    public void testCeil3() throws Exception {
        // conflict between DoM and DoW. In this we need to find a day that's the first day of a month and Sunday
        CronTab x = new CronTab("0 0 1 * 0");
        Calendar c = new GregorianCalendar(2010, Calendar.JANUARY, 1, 15, 55);
        // the first such day in 2010 is Aug 1st
        compare(new GregorianCalendar(2010, Calendar.AUGUST, 1, 0, 0), x.ceil(c));
    }