indexer.storage: Change return types from Iterable to List
For consistency with the main storage.
Depends on !263 (closed).
Migrated from D4174 (view on Phabricator)
Staging instance, all changes can be removed at any time
For consistency with the main storage.
Depends on !263 (closed).
Migrated from D4174 (view on Phabricator)