@Override
    public int hashCode() {
        return Objects.hash(
            kraftControllerId,
            kraftControllerEpoch,
            kraftMetadataOffset,
            kraftMetadataEpoch,
            lastUpdatedTimeMs,
            migrationZkVersion,
            zkControllerEpoch,
            zkControllerEpochZkVersion);
    }
A Kafka-internal constant used to indicate that the znode version is unknown. See ZkVersion.UnknownVersion.
metadata/src/main/java/org/apache/kafka/metadata/migration/ZkMigrationLeadershipState.java