/**
     * Get the Retry-After header value in seconds.
     * @return the retry after seconds
     */
    public int getRetryAfterSeconds() {
        return ComponentUtil.getFessConfig().getRateLimitRetryAfterSecondsAsInteger();
    }

    /**
     * Block an IP address for the specified duration.
     * Note: The duration is ignored as the cache uses the configured block duration.
     * @param ip the IP address to block

     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     * @throws NumberFormatException When the property is not integer.
     */
    Integer getRateLimitRetryAfterSecondsAsInteger();

    /**
     * Get the value for the key 'rate.limit.whitelist.ips'. <br>
     * The value is, e.g. 127.0.0.1,::1 <br>