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