presto-hive/src/main/java/io/prestosql/plugin/hive/HiveSplitSource.java/HiveSplitSource/toBucketNumber
class HiveSplitSource:    private static OptionalInt toBucketNumber(ConnectorPartitionHandle partitionHandle)
    {
        if (partitionHandle == NOT_PARTITIONED) {
            return OptionalInt.empty();
        }
        return OptionalInt.of(((HivePartitionHandle) partitionHandle).getBucket());
    }