@BeforeEach
    public void startClusters() throws Exception {
        mm2Props.put(
                PRIMARY_CLUSTER_ALIAS + "." + DistributedConfig.EXACTLY_ONCE_SOURCE_SUPPORT_CONFIG,
                DistributedConfig.ExactlyOnceSourceSupport.ENABLED.toString()
        );
        mm2Props.put(
                BACKUP_CLUSTER_ALIAS + "." + DistributedConfig.EXACTLY_ONCE_SOURCE_SUPPORT_CONFIG,
                DistributedConfig.ExactlyOnceSourceSupport.ENABLED.toString()
        );
        for (Properties brokerProps : Arrays.asList(primaryBrokerProps, backupBrokerProps)) {
            brokerProps.put("transaction.state.log.replication.factor", "1");
            brokerProps.put("transaction.state.log.min.isr", "1");
        }
        super.startClusters();
    }
Tests MM2 replication with exactly-once support enabled on the Connect clusters.
connect/mirror/src/test/java/org/apache/kafka/connect/mirror/integration/MirrorConnectorsIntegrationExactlyOnceTest.java