public static String dateString(long timeMs, ZoneOffset zoneOffset) {
        return new Date(timeMs).toInstant().
            atOffset(zoneOffset).
            format(DateTimeFormatter.ISO_OFFSET_DATE_TIME);
    }
@Test
    public void testDateString() {
        assertEquals("2019-01-08T20:59:29.85Z", dateString(1546981169850L, ZoneOffset.UTC));
    }