code: public static final String[] getKeywordValues(String keyword) {
          if (!keyword.equals(KEYWORDS[0])) {
              throw new IllegalArgumentException("Invalid keyword: " + keyword);
          }
          return ICUResourceBundle.getKeywordValues(BASE, RESOURCE);
      }
docs: <strong>[icu]</strong> Given a keyword, returns an array of all values for
  that keyword that are currently in use.
  @param keyword one of the keywords returned by getKeywords.
  @see #getKeywords