presto-main/src/main/java/io/prestosql/sql/planner/NodePartitionMap.java/NodePartitionMap/NodePartitionMap
class NodePartitionMap:    public NodePartitionMap(List<InternalNode> partitionToNode, ToIntFunction<Split> splitToBucket)
    {
        this.partitionToNode = ImmutableList.copyOf(requireNonNull(partitionToNode, "partitionToNode is null"));
        this.bucketToPartition = IntStream.range(0, partitionToNode.size()).toArray();
        this.splitToBucket = requireNonNull(splitToBucket, "splitToBucket is null");
    }