* @return true if the IP is a trusted proxy
     */
    protected boolean isTrustedProxy(final String ip) {
        final Set<String> trustedProxies = ComponentUtil.getFessConfig().getRateLimitTrustedProxiesAsSet();
        final boolean trusted = trustedProxies.contains(ip);
        if (logger.isDebugEnabled() && trusted) {
            logger.debug("Trusted proxy detected: ip={}", ip);
        }