@Test
    public void testBootstrapZkMigrationRecord() throws Exception {
        assertEquals(ZkMigrationState.PRE_MIGRATION,
            checkBootstrapZkMigrationRecord(MetadataVersion.IBP_3_4_IV0, true));

        assertEquals(ZkMigrationState.NONE,
            checkBootstrapZkMigrationRecord(MetadataVersion.IBP_3_4_IV0, false));

        assertEquals(ZkMigrationState.NONE,
            checkBootstrapZkMigrationRecord(MetadataVersion.IBP_3_3_IV0, false));

        assertEquals(
            "The bootstrap metadata.version 3.3-IV0 does not support ZK migrations. Cannot continue with ZK migrations enabled.",
            assertThrows(FaultHandlerException.class, () ->
                checkBootstrapZkMigrationRecord(MetadataVersion.IBP_3_3_IV0, true)).getCause().getMessage()
        );
    }
Test that certain controller operations finish immediately without putting an event
on the controller queue, if there is nothing to do.
metadata/src/test/java/org/apache/kafka/controller/QuorumControllerTest.java