@VisibleForTesting
    static final boolean isIPv6(String ip) {
        return ip.split(":", -1).length == 8;
    }
Collects counts statistics about the request: client ip address from the x-forwarded-for header;
ipv4 or ipv6 and  host name from the host header;

@param req
zuul-core/src/main/java/com/netflix/zuul/stats/StatsManager.java