docs: public static <T extends Comparable<T>> String toSortedByKeysString(Counter<T> counter, String itemFormat, String joiner, String wrapperFormat) {
      List<String> strings = new ArrayList<String>();
      for (T key : CollectionUtils.sorted(counter.keySet())) {
        strings.add(String.format(itemFormat, key, counter.getCount(key)));
      }
      return String.format(wrapperFormat, StringUtils.join(strings, joiner));
    }