public static Optional<ZkMigrationState> optionalOf(byte value) {
        for (ZkMigrationState state : ZkMigrationState.values()) {
            if (state.value == value) {
                return Optional.of(state);
            }
        }
        return Optional.empty();
    }
The controller is a ZK controller. No migration has been performed. This state is never persisted
and is only used by KafkaController in order to have a unified metric that indicates what kind of
metadata state the controller is in.
metadata/src/main/java/org/apache/kafka/metadata/migration/ZkMigrationState.java