@Override
    public ControlledShutdownResponseData data() {
        return data;
    }
Possible error codes:

UNKNOWN(-1) (this is because IllegalStateException may be thrown in `KafkaController.shutdownBroker`, it would be good to improve this)
BROKER_NOT_AVAILABLE(8)
STALE_CONTROLLER_EPOCH(11)
clients/src/main/java/org/apache/kafka/common/requests/ControlledShutdownResponse.java