protected T removeClient(Server server) {
        T client = rxClientCache.remove(server);
        if (client != null) {
            client.shutdown();
        }
        return client;
    }
Remove the client for this Server
@param server
@return The RxClient implementation or null if not found
ribbon-transport/src/main/java/com/netflix/ribbon/transport/netty/LoadBalancingRxClient.java