Add some user metadata in generated ORC files
add:
- object type
- uuid
- version of swh.model used at file generation time,
- version of swh.dataset used at file generation time.
Depends on !37 (closed).
Migrated from D7384 (view on Phabricator)
add:
Depends on !37 (closed).
Migrated from D7384 (view on Phabricator)