public void stop() {
        AtomicReference<Throwable> shutdownFailure = new AtomicReference<>();
        Utils.closeQuietly(producer, "producer for embedded Kafka cluster", shutdownFailure);
        Utils.closeQuietly(cluster, "embedded Kafka cluster", shutdownFailure);
        if (shutdownFailure.get() != null) {
            throw new ConnectException("Failed to shut down producer / embedded Kafka cluster", shutdownFailure.get());
        }
    }
Stop only the Kafka brokers (and not the KRaft controllers). This can be used to test Connect's functionality
when the backing Kafka cluster goes offline.
connect/runtime/src/test/java/org/apache/kafka/connect/util/clusters/EmbeddedKafkaCluster.java