Trusted subnets should be checked only if option is enabled

[hc4]

Problem description

Currently trusted subnets checked even if checking disabled.

Should be checked only if option enabed:

if (config.requireTrustedProxies()) {
    final boolean inTrustedSubnets = trustedProxies.stream()
        .anyMatch(ipSubnet -> {
            try {
                return ipSubnet.contains(headersToken.getRemoteAddr());
            } catch (UnknownHostException ignored) {
                LOG.debug("Looking up remote address {} failed.", headersToken.getRemoteAddr());
                return false;
            }
        });
    if(!inTrustedSubnets) {     
        LOG.info("Request with trusted header {} received from {} which is not in the trusted subnets: {}",
             usernameHeader,
             headersToken.getRemoteAddr(),
             Joiner.on(", ").join(trustedProxies));
        return null;
    }
}

Environment

• Graylog Version: 2.1.0-beta2
• Plugin Version: 1.0.0 snapshot