code: public static HiveColumnHandle bucketColumnHandle()
      {
          return new HiveColumnHandle(BUCKET_COLUMN_NAME, BUCKET_HIVE_TYPE, BUCKET_TYPE_SIGNATURE, BUCKET_COLUMN_INDEX, SYNTHESIZED, Optional.empty());
      }
docs: The column indicating the bucket id.
  When table bucketing differs from partition bucketing, this column indicates
  what bucket the row will fall in under the table bucketing scheme.