code: public static String formatIsoDate(Instant date) {
          return CONSISTENT_ISO_INSTANT.format(date.atZone(ZoneOffset.UTC));
      }
docs: Use this instead of Instant.toString() to ensure you always end up with the same pattern instead of 'smartly'
  loosing fractionals depending on what time it is.
  
  @param date
  an instant
  @return iso instant of the form "1974-10-20T00:00:00.000Z" with 3 fractionals, always.