private void prepareFindCoordinatorResponse(Errors error, String txnid) {
        Node node = metadata.fetch().nodes().get(0);
        client.prepareResponse(FindCoordinatorResponse.prepareResponse(error, txnid, node));
    }
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