Error when configuring synchronous broker mirroring

Issue

• When tried to configure the 2nd broker as a synchronous mirror of the 1st one by adding the following configuration to the broker.xml of the 1st broker:

<broker-connections>
   <amqp-connection uri="tcp://service_name:5672" name="DC2" user="admin" password="******" sync="true">
      <mirror/>
   </amqp-connection>
</broker-connections>

• After adding this configuration the 1st broker doesn't start anymore and the logfile shows the following error:

2023-07-17 05:06:49,908 ERROR [org.apache.activemq.artemis.core.client] AMQ214019: Invalid configuration
org.xml.sax.SAXParseException: cvc-complex-type.3.2.2: Attribute 'sync' is not allowed to appear in element 'amqp-connection'.