@Override
    public CompletableFuture<Void> shutdown(int timeoutMs) {
        logger.info("Beginning graceful shutdown");
        CompletableFuture<Void> shutdownComplete = new CompletableFuture<>();
        shutdown.set(new GracefulShutdown(timeoutMs, shutdownComplete));
        wakeup();
        return shutdownComplete;
    }
Poll for new events. This allows the client to handle inbound
requests and send any needed outbound requests.
raft/src/main/java/org/apache/kafka/raft/KafkaRaftClient.java