}

    String getOnlineHelpSupportedLangs();

    default boolean isOnlineHelpSupportedLang(final String lang) {
        if (StringUtil.isBlank(getOnlineHelpSupportedLangs())) {
            return false;
        }
        return split(getOnlineHelpSupportedLangs(), ",").get(stream -> stream.filter(StringUtil::isNotBlank).anyMatch(s -> s.equals(lang)));
    }

     * The value is, e.g. ja <br>
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getOnlineHelpSupportedLangs();

    /**
     * Get the value for the key 'forum.link'. <br>
     * The value is, e.g. https://discuss.codelibs.org/c/Fess{lang}/ <br>