Simple connection error code

gistfile1.txt

            FetchRequest req = new FetchRequestBuilder()
                    .clientId(clientId)
                    .addFetch(topic, partition, offset, fetchSize)
                    .minBytes(1)
                    .maxWait(250)
                    .build();
            FetchResponse resp = underlying.fetch(req);
            if(resp.hasError()) {
                int code =  resp.errorCode(topic, partition);
                if (code == 9) {
                    logger.warn("Fetch response contained error code: {}", resp.errorCode(topic, partition));
                } else {
                    throw new RuntimeException(String.format("Fetch response contained error code %d", code));
                }
            }