@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        ZkMigrationLeadershipState that = (ZkMigrationLeadershipState) o;
        return kraftControllerId == that.kraftControllerId
            && kraftControllerEpoch == that.kraftControllerEpoch
            && kraftMetadataOffset == that.kraftMetadataOffset
            && kraftMetadataEpoch == that.kraftMetadataEpoch
            && lastUpdatedTimeMs == that.lastUpdatedTimeMs
            && migrationZkVersion == that.migrationZkVersion
            && zkControllerEpoch == that.zkControllerEpoch
            && zkControllerEpochZkVersion == that.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