default CompletableFuture<FetchResult> fetch(long startOffset, long endOffset) {
        return fetch(startOffset, endOffset, (int) (endOffset - startOffset));
    }
Fetch record batch from stream slice.

@param startOffset  start offset.
@param endOffset    end offset.
@param maxBytesHint max fetch data size hint, the real return data size may be larger than maxBytesHint.
@return {@link FetchResult}
core/src/main/scala/kafka/log/streamaspect/ElasticStreamSlice.java