presto-main/src/main/java/io/prestosql/split/BufferingSplitSource.java/BufferingSplitSource/fetchNextBatchAsync
class BufferingSplitSource:        public static ListenableFuture<SplitBatch> fetchNextBatchAsync(
                SplitSource splitSource,
                int min,
                int max,
                ConnectorPartitionHandle partitionHandle,
                Lifespan lifespan)
        {
            GetNextBatch getNextBatch = new GetNextBatch(splitSource, min, max, partitionHandle, lifespan);
            ListenableFuture<?> future = getNextBatch.fetchSplits();
            return Futures.transform(future, ignored -> new SplitBatch(getNextBatch.splits, getNextBatch.noMoreSplits), directExecutor());
        }