protected String getUserCodeFromRequest(final HttpServletRequest request) {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final String userCode = request.getParameter(fessConfig.getUserCodeRequestParameter());
        if (StringUtil.isBlank(userCode)) {
            return null;
        }

        if (fessConfig.isValidUserCode(userCode)) {
            request.setAttribute(Constants.USER_CODE, userCode);

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

    /**
     * Get the value for the key 'user.code.min.length'. <br>
     * The value is, e.g. 20 <br>