Remove attribute APIBase._collection
Motivation:
- It was used only internally in checks() and in 'POST Col-IRI'
- A method named "check" should not set attributes
Depends on !170 (closed).
Migrated from D4586 (view on Phabricator)
Staging instance, all changes can be removed at any time
Motivation:
Depends on !170 (closed).
Migrated from D4586 (view on Phabricator)