code: public static <V> int longestKeyLength(Map<String, V> map) {
      if (map.isEmpty()) {
        return 0;
      }
  
      return Ordering.natural().max(
          FluentIterable.from(map.keySet())
              .transform(StringUtils.lengthFunction()));
    }
docs: Returns the length of the longest key in a map, or 0 if the map is empty. Useful for printing
  tables, etc. The map may not have any null keys.