@Override
    public boolean apply(@Nullable PredicateKey input) {
        LoadBalancerStats stats = getLBStats();
        if (stats == null) {
            return true;
        }
        return !shouldSkipServer(stats.getSingleServerStat(input.getServer()));
    }
Predicate with the logic of filtering out circuit breaker tripped servers and servers 
with too many concurrent connections from this client.

@author awang
ribbon-loadbalancer/src/main/java/com/netflix/loadbalancer/AvailabilityPredicate.java