public static String dateString(long timeMs, ZoneOffset zoneOffset) {
        return new Date(timeMs).toInstant().
            atOffset(zoneOffset).
            format(DateTimeFormatter.ISO_OFFSET_DATE_TIME);
    }
Pretty-print a date string.

@param timeMs        The time since the epoch in milliseconds.
@param zoneOffset    The time zone offset.
@return              The date string in ISO format.
trogdor/src/main/java/org/apache/kafka/trogdor/common/StringFormatter.java