// InitProducerIDRequest initializes a producer ID for idempotent transactions,
// and if using transactions, a producer epoch. This is the first request
// necessary to begin idempotent producing or transactions.
//
// Note that you do not need to go to a txn coordinator if you are initializing
// a producer id without a transactional id.
InitProducerIDRequest => key 22, max version 4, flexible v2+, txn coordinator
  // TransactionalID is the ID to use for transactions if using transactions.
  TransactionalID: nullable-string
  // TransactionTimeoutMillis is how long a transaction is allowed before
  // EndTxn is required.
  //
  // Note that this timeout only begins on the first AddPartitionsToTxn
  // request.
  TransactionTimeoutMillis: int32
  // ProducerID, added for KIP-360, is the current producer ID. This allows
  // the client to potentially recover on UNKNOWN_PRODUCER_ID errors.
  ProducerID: int64(-1) // v3+
  // The producer's current epoch. This will be checked against the producer
  // epoch on the broker, and the request will return an error if they do not
  // match. Also added for KIP-360.
  ProducerEpoch: int16(-1) // v3+

// InitProducerIDResponse is returned for an InitProducerIDRequest.
InitProducerIDResponse =>
  ThrottleMillis(1)
  // CLUSTER_AUTHORIZATION_FAILED is returned when not using transactions if
  // the client is not authorized for idempotent_write on cluster.
  //
  // TRANSACTIONAL_ID_AUTHORIZATION_FAILED is returned when using transactions
  // if the client is not authorized to write on transactional_id.
  //
  // INVALID_REQUEST is returned if using transactions and the transactional id
  // is an empty, non-null string
  //
  // COORDINATOR_LOAD_IN_PROGRESS is returned if the coordinator for this
  // transactional ID is still loading.
  //
  // NOT_COORDINATOR is returned if the broker is not the coordinator for
  // this transactional ID.
  //
  // INVALID_TRANSACTION_TIMEOUT is returned if using transactions and the timeout
  // is equal to over over transaction.max.timeout.ms or under 0.
  //
  // CONCURRENT_TRANSACTIONS is returned if there is an ongoing transaction
  // that is completing at the time this init is called.
  ErrorCode: int16
  // ProducerID is the next producer ID that Kafka generated. This ID is used
  // to ensure repeated produce requests do not result in duplicate records.
  ProducerID: int64(-1)
  // ProducerEpoch is the producer epoch to use for transactions.
  ProducerEpoch: int16