          Providing other formats, like space-separated bootstrap servers (e.g., <code>host1:port1 host2:port2 host3:port3</code>), will result in an exception, even though this was allowed in Apache Kafka versions prior to 4.0.
                        </li>
                    </ul>
                </li>
                <li><a id="upgrade_400_notable_broker" href="#upgrade_400_notable_broker"><b>Broker</b></a>
                    <ul>
                        <li>The <code>delegation.token.master.key</code>