code: @FromString
      public static UtcInstant parse(CharSequence text) {
          TemporalAccessor parsed = DateTimeFormatter.ISO_INSTANT.parse(text);
          long epochSecond = parsed.getLong(INSTANT_SECONDS);
          long nanoOfSecond = parsed.getLong(NANO_OF_SECOND);
          boolean leap = parsed.query(DateTimeFormatter.parsedLeapSecond());
          long epochDay = Math.floorDiv(epochSecond, SECS_PER_DAY);
          long mjd = epochDay + OFFSET_MJD_EPOCH;
          long nanoOfDay = Math.floorMod(epochSecond, SECS_PER_DAY) * NANOS_PER_SECOND + nanoOfSecond;
          if (leap) {
              nanoOfDay += NANOS_PER_SECOND;
          }
          return UtcInstant.ofModifiedJulianDay(mjd, nanoOfDay);
      }
docs: Obtains an instance of {@code UtcInstant} from a text string
  {@code 2007-12-03T10:15:30.00Z}.
  <p>
  The string must represent a valid instant in UTC and is parsed using
  {@link DateTimeFormatter#ISO_INSTANT} with leap seconds handled.
  
  @param text  the text to parse such as "12345.123456789s(TAI)", not null
  @return the parsed instant, not null
  @throws DateTimeParseException if the text cannot be parsed
  @throws DateTimeException if parsed text represents an invalid leap second