code: private static String[] splitRangeUnit(final String str) {
      if(StringUtils.isBlank(str)) {
        return new String[]{""};
      }
      return str.split(RANGE_UNIT_PATTERN);
    }
docs: Return the string array that has been split using {@link #RANGE_UNIT_PATTERN}
  
  @param str string to split
  
  @return string array that has been split using {@link #RANGE_UNIT_PATTERN}