public ApiKeys apiKey() {
        return requestBuilder.apiKey();
    }
@param destination The brokerId to send the request to
@param requestBuilder The builder for the request to make
@param correlationId The correlation id for this client request
@param clientId The client ID to use for the header
@param createdTimeMs The unix timestamp in milliseconds for the time at which this request was created.
@param expectResponse Should we expect a response message or is this request complete once it is sent?
@param callback A callback to execute when the response has been received (or null if no callback is necessary)
clients/src/main/java/org/apache/kafka/clients/ClientRequest.java