### Question:
TimeUtil { public static String formatCcsdsUtcMillisFormat(Date time) { if (time == null) { return ""; } return CCSDS_UTC_MILLIS_FORMAT.format(time); } private  TimeUtil(); static String formatCcsdsUtcFormat(Date time); static String formatCcsdsUtcMillisFormat(Date time); static Date parseCcsdsUtcFormat(String timeString); static String formatIsoUtcFormat(Date time); static Date parseInsituFileNameDateFormat(String timeString); static String formatInsituFilenameFormat(Date time); static Date parseShortUtcFormat(String timeString); static String formatShortUtcFormat(Date time); static Date julianDateToDate(double julianDate); static double dateToSecondsSinceEpoch(Date date); static double julianDateToSecondsSinceEpoch(double julianDate); static double toJulianDate(Date date); static Date secondsSince1981ToDate(double secondsSince1981); static long toSecondsSince1978(Date time); static Date secondsSince1978ToDate(double secondsSince1978); static double secondsSince1981ToSecondsSinceEpoch(double secondsSince1981); static double millisToSecondsSinceEpoch(long millis); static int intMillisToSecondsSinceEpoch(long millis); static boolean checkTimeOverlap(Date time, Date start, Date end, double timeDelta); static double getTimeDifferenceInSeconds(Date d, Date d2); static Date getCenterTime(Date startTime, Date endTime); static double getTimeRadius(Date startTime, Date endTime); static Calendar createCalendarAtBeginningOfYear(int year); static Date getBeginningOfDay(Date day); static Date getEndOfDay(Date day); static GregorianCalendar createUtcCalendar(); static GregorianCalendar createUtcCalendar(Date date); static int getYear(Date date); static int getDayOfYear(Date date); static int getMonth(Date date); static Date getBeginOfMonth(Date date); static Date getEndOfMonth(Date date); static final double EPOCH_JD; static final double MILLIS_PER_DAY; static final long MILLIS_1978; static final long MILLIS_1981; static final double SECONDS_PER_DAY; }### Answer:
@Test public void testFormatCcsdsUtcMillisFormat() { final GregorianCalendar calendar = new GregorianCalendar(TimeZone.getTimeZone("UTC")); calendar.set(Calendar.YEAR, 2010); calendar.set(Calendar.DAY_OF_YEAR, 1); calendar.set(Calendar.HOUR_OF_DAY, 0); calendar.set(Calendar.MINUTE, 0); calendar.set(Calendar.SECOND, 0); calendar.set(Calendar.MILLISECOND, 46800000); assertEquals("2010-01-01T13:00:00.000Z", TimeUtil.formatCcsdsUtcMillisFormat(calendar.getTime())); }
@Test public void testFormatCcsdsUtcMillisFormat_nullInput() { assertEquals("", TimeUtil.formatCcsdsUtcMillisFormat(null)); }