public static FetchResponse of(Errors error,
                                   int throttleTimeMs,
                                   int sessionId,
                                   LinkedHashMap<TopicIdPartition, FetchResponseData.PartitionData> responseData) {
        return new FetchResponse(toMessage(error, throttleTimeMs, sessionId, responseData.entrySet().iterator(), Collections.emptyList()));
    }
@return The size in bytes of the records. 0 is returned if records of input partition is null.
clients/src/main/java/org/apache/kafka/common/requests/FetchResponse.java