code: public static Duration convertToISODuration(final String timeInterval) {
          return Duration.between(LocalTime.MIN, convertDurationToLocalTime(timeInterval));
      }
docs: Convert the time interval or duration specified in "HH:mm:ss" format to
  ISO format.
  
  @param timeInterval
  in "HH:mm:ss" string format. This format is popularly used but
  can be confused with time of the day, hence conversion to ISO
  specified format for time duration is required.
  
  @return {@link Duration} in ISO format.
  
  @throws DateTimeParseException
  if the text cannot be converted to ISO format.