// For KIP-664, ListTransactionsRequest lists transactions.
ListTransactionsRequest => key 66, max version 0, flexible v0+
  // The transaction states to filter by: if empty, all transactions are
  // returned; if non-empty, then only transactions matching one of the
  // filtered states will be returned.
  //
  // For a list of valid states, see the TransactionState enum.
  StateFilters: [string]
  // The producer IDs to filter by: if empty, all transactions will be
  // returned; if non-empty, only transactions which match one of the filtered
  // producer IDs will be returned
  ProducerIDFilters: [int64]

// ListTransactionsResponse is a response to a ListTransactionsRequest.
ListTransactionsResponse =>
  ThrottleMillis
  // A potential error code for the listing,
  //
  // COORDINATOR_LOAD_IN_PROGRESS is returned if the coordinator is loading.
  //
  // COORDINATOR_NOT_AVAILABLE is returned if the coordinator receiving this
  // request is shutting down.
  ErrorCode: int16
  // Set of state filters provided in the request which were unknown to the
  // transaction coordinator.
  UnknownStateFilters: [string]
  // TransactionStates contains all transactions that were matched for listing
  // in the request. The response elides transactions that the user does not have
  // permission to describe (DESCRIBE on TRANSACTIONAL_ID for the transaction).
  TransactionStates: [=>]
    // The transactional ID being used.
    TransactionalID: string
    // The producer ID of the producer.
    ProducerID: int64
    // The current transaction state of the producer.
    TransactionState: string