protected void after() {
        if (server != null) {
            try {
                server.shutdown();
            } catch (InterruptedException e) {
                LOG.error("Failed to shut down server", e);
            }
        }
    }
Override to tear down your specific external resource.
ribbon-transport/src/test/java/com/netflix/client/netty/udp/HelloUdpServerExternalResource.java