code: public static String changeTimestampToNewFormatWithDefaultZoneId(
              String isoTimestamp, DateTimeFormatter newFormat) {
          return changeTimestampToNewFormat(isoTimestamp,
                  getZoneId(DEFAULT_ZONE_ID), newFormat);
      }
docs: Change timestamp to new format with default zone id string.
  
  @param isoTimestamp the iso timestamp
  @param newFormat    the new format
  @return the string