presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/RaptorNodePartitioningProvider.java/RaptorNodePartitioningProvider/getSplitBucketFunction
class RaptorNodePartitioningProvider:    @Override
    public ToIntFunction<ConnectorSplit> getSplitBucketFunction(ConnectorTransactionHandle transaction, ConnectorSession session, ConnectorPartitioningHandle partitioning)
    {
        return value -> ((RaptorSplit) value).getBucketNumber().getAsInt();
    }