presto-main/src/main/java/io/prestosql/operator/PartitionedLookupSourceFactory.java/PartitionedLookupSourceFactory/loadSpilledLookupSource
class PartitionedLookupSourceFactory:    private ListenableFuture<Supplier<LookupSource>> loadSpilledLookupSource(int partitionNumber)
    {
        return getSpilledLookupSourceHandle(partitionNumber).getLookupSource();
    }