private ZoneStats getZoneStats(String zone) {
        zone = zone.toLowerCase();
        ZoneStats zs = zoneStatsMap.get(zone);
        if (zs == null){
            zoneStatsMap.put(zone, new ZoneStats(this.getName(), zone, this));
            zs = zoneStatsMap.get(zone);
        }
        return zs;
    }
Method that updates the internal stats of Response times maintained on a per Server
basis
@param server
@param msecs
ribbon-loadbalancer/src/main/java/com/netflix/loadbalancer/LoadBalancerStats.java