{
  "apiKey": 22,
  "type": "request",
  "listeners": ["broker"],
  "name": "InitProducerIdRequest",
  // Version 1 is the same as version 0.
  //
  // Version 2 is the first flexible version.
  //
  // Version 3 adds ProducerId and ProducerEpoch, allowing producers to try to resume after an INVALID_PRODUCER_EPOCH error
  //
  // Version 4 adds the support for new error code PRODUCER_FENCED.
  //
  // Version 5 adds support for new error code TRANSACTION_ABORTABLE (KIP-890).
  //
  // Version 6 adds support for 2PC (KIP-939).
  //
  // Version 7 adds support for transaction heartbeats (KIP-1309).
  "validVersions": "0-7",
  "flexibleVersions": "2+",
  "fields": [
    { "name": "TransactionalId", "type": "string", "versions": "0+", "nullableVersions": "0+", "entityType": "transactionalId",
      "about": "The transactional id, or null if the producer is not transactional." },
    { "name": "TransactionTimeoutMs", "type": "int32", "versions": "0+",
      "about": "The time in ms to wait before aborting idle transactions sent by this producer. This is only relevant if a TransactionalId has been defined." },
    { "name": "TransactionHeartbeatIntervalMs", "type": "int32", "versions": "7+", "default": "0", "ignorable": "true",
      "about": "The time in ms between heartbeats from the producer. If >0, idle transactions sent by this producer are aborted after 3 times this interval." },
    { "name": "ProducerId", "type": "int64", "versions": "3+", "default": "-1", "entityType": "producerId",
      "about": "The producer id. This is used to disambiguate requests if a transactional id is reused following its expiration." },
    { "name": "ProducerEpoch", "type": "int16", "versions": "3+", "default": "-1",
      "about": "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." },
    { "name": "Enable2Pc", "type": "bool", "versions": "6+", "default": "false",
      "about": "True if the client wants to enable two-phase commit (2PC) protocol for transactions." },
    { "name": "KeepPreparedTxn", "type": "bool", "versions": "6+", "default": "false",
      "about": "True if the client wants to keep the currently ongoing transaction instead of aborting it." }

  ]
}

{
  "apiKey": TBD,
  "type": "request",
  "listeners": ["broker"],
  "name": "TxnHeartbeatRequest",
  // Version 0 is the first version (KIP-1309).
  "validVersions": "0",
  "flexibleVersions": "0+",
  "fields": [
    { "name": "TransactionalId", "type": "string", "versions": "0+", "entityType": "transactionalId",
      "about": "The transactional id." },
    { "name": "ProducerId", "type": "int64", "versions": "0+", "default": "-1", "entityType": "producerId",
      "about": "The producer id. This is used to disambiguate requests if a transactional id is reused following its expiration." },
    { "name": "ProducerEpoch", "type": "int16", "versions": "0+", "default": "-1",
      "about": "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." },
  ]
}

{
  "apiKey": TBD,
  "type": "response",
  "name": "TxnHeartbeatResponse",
  // Version 0 is the first version (KIP-1309).
  "validVersions": "0",
  "flexibleVersions": "0+",
  // Supported errors:
  // - TRANSACTIONAL_ID_AUTHORIZATION_FAILED (version 0+)
  // - TRANSACTIONAL_ID_NOT_FOUND (version 0+)
  // - NOT_COORDINATOR (version 0+) 
  // - COORDINATOR_NOT_AVAILABLE (version 0+)
  // - COORDINATOR_LOAD_IN_PROGRESS (version 0+)
  // - INVALID_REQUEST (version 1+)
  "fields": [
    { "name": "ThrottleTimeMs", "type": "int32", "versions": "0+", "ignorable": true,
      "about": "The duration in milliseconds for which the request was throttled due to a quota violation, or zero if the request did not violate any quota." },
    { "name": "ErrorCode", "type": "int16", "versions": "0+",
      "about": "The error code, or 0 if there was no error." },
    { "name": "ErrorMessage", "type": "string", "versions": "0+", "nullableVersions": "0+", "default": "null",
      "about": "The error message, or null if there was no error." }
  ]
}