presto-main/src/main/java/io/prestosql/operator/PartitionedLookupSourceFactory.java/PartitionedLookupSourceFactory/SpillingInfo
class PartitionedLookupSourceFactory:        SpillingInfo(long spillEpoch, Set<Integer> spilledPartitions)
        {
            this.spillEpoch = spillEpoch;
            this.spilledPartitions = ImmutableSet.copyOf(requireNonNull(spilledPartitions, "spilledPartitions is null"));
        }