Deletion of latest auto_update revision removes object completely from collection

[das-Abroxas]

Describe the bug

Deletion of an object with more than one revision and only a single auto_update: true reference removes the object completely from a collection.

To Reproduce

Steps to reproduce the behavior:

1. Create collection with an object which has at least two revisions and only an auto_update: true reference
2. Delete latest resvision with a DeleteObjectRequest
3. Get all objects of collection with a GetObjectsRequest
4. Response is empty

Expected behavior

After deleting the latest revision with the last auto_update: true reference, actually the older references are still present in the collection. Therefore, it would make sense if the reference is not simply removed, but updated to the next lower, undeleted revision.