code: public static String jodaFormat( ZonedDateTime dateTime ) {
          CheckArg.isNotNull(dateTime, "dateTime");
          return dateTime.format(JODA_ISO8601_FORMATTER);
      }
docs: Returns the ISO8601 string of a given date-time instance with timezone information, trying to be as closed as possible
  to what the JODA date-time library would return.
  
  @param dateTime a {@link ZonedDateTime} instance, may not be null
  @return a {@link String} representation of the date instance according to the ISO8601 standard