private void prepareInitProducerResponse(Errors error, long producerId, short producerEpoch) {
        client.prepareResponse(initProducerIdResponse(producerId, producerEpoch, error));
    }
It creates response with new leader info and new nodes, as stated in KIP-951
clients/src/test/java/org/apache/kafka/clients/producer/internals/SenderTest.java