presto-main/src/main/java/io/prestosql/spiller/PartitioningSpiller.java/PartitioningSpillResult/PartitioningSpillResult
class PartitioningSpillResult:        public PartitioningSpillResult(ListenableFuture<?> spillingFuture, Page retained)
        {
            this.spillingFuture = requireNonNull(spillingFuture, "spillingFuture is null");
            this.retained = requireNonNull(retained, "retained is null");
        }