Review

class LocaleUtils {
    /**
     * <p>Obtains an unmodifiable set of installed locales.</p>
     * 
     * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
     * It is more efficient, as the JDK method must create a new array each
     * time it is called.</p>
     *
     * @return the unmodifiable set of available locales
     */
    public static Set availableLocaleSet() {
        Set set = cAvailableLocaleSet;
        if (set == null) {
            set = new HashSet(availableLocaleList());
            set = Collections.unmodifiableSet(set);
            cAvailableLocaleSet = set;
        }
        return set;
    }

}