async initProducerId({ transactionalId, transactionTimeout }) {
    const initProducerId = this.lookupRequest(apiKeys.InitProducerId, requests.InitProducerId)
    return await this[PRIVATE.SEND_REQUEST](initProducerId({ transactionalId, transactionTimeout }))
  }
Send an `InitProducerId` request to fetch a PID and bump the producer epoch.

Request should be made to the transaction coordinator.
@public
@param {object} request
@param {number} request.transactionTimeout The time in ms to wait for before aborting idle transactions
@param {number} [request.transactionalId] The transactional id or null if the producer is not transactional
@returns {Promise}