code: public SortedMap<String, String> getDisplayNames() {
          ULocale locale = ULocale.getDefault(Category.DISPLAY);
          return getDisplayNames(locale, null, null);
      }
docs: Convenience override of getDisplayNames(ULocale, Comparator, String) that
  uses the current default Locale as the locale, null as
  the comparator, and null for the matchID.