* comment: Base link for online help.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getOnlineHelpBaseLink();

    /**
     * Get the value for the key 'online.help.installation'. <br>
     * The value is, e.g. https://fess.codelibs.org/{lang}/{version}/install/install.html <br>