code: public String getRuleSetDisplayName(String ruleSetName, ULocale loc) {
          String[] rsnames = publicRuleSetNames;
          for (int ix = 0; ix < rsnames.length; ++ix) {
              if (rsnames[ix].equals(ruleSetName)) {
                  String[] names = getNameListForLocale(loc);
                  if (names != null) {
                      return names[ix];
                  }
                  return rsnames[ix].substring(1);
              }
          }
          throw new IllegalArgumentException("unrecognized rule set name: " + ruleSetName);
      }
docs: Return the rule set display name for the provided rule set and locale.
  The locale is matched against the locales for which there is display name data, using
  normal fallback rules.  If no locale matches, the default display name is returned.
  @return the display name for the rule set
  @see #getRuleSetDisplayNames
  @throws IllegalArgumentException if ruleSetName is not a valid rule set name for this format