'Guestbook at Access Request' creates empty responses when configured for datasets with open files (and vice versa)

What steps does it take to reproduce the issue?

• For a given Dataverse Collection, set 'Guestbook Entry Option' to 'Guestbook Entry at Access Request'.
• Create a Guestbook.
• Create a dataset with open files and activate the guestbook. Publish the dataset.
• Log out and access the dataset as visitor.
• Download one or more files from the dataset.

The guestbook does not appear (as expected for 'Guestbook Entry at Access Request').

• Log in again and access the guestbook panel for the Dataverse Collection.
• The guestbook has now one response, which is completely empty.

The same thing happens the other way round (combination of 'Guestbook Entry at Download' with restricted files).

• When does this issue occur?
  See above.

• Which page(s) does it occurs on?
  Guestbooks statistics for a Dataverse Collection.

• What happens?
  See above.

• To whom does it occur (all users, curators, superusers)?
  Collection admins.

• What did you expect to happen?

1. With the 'Guestbook Entry at Access Request' option, it should not be able to activate the guestbook for datasets with open files in the first place (and the other way round for 'Guestbook Entry at Download' and datasets with restricted files).
2. Guestbooks should not automatically create empty responses when not prompted.

Which version of Dataverse are you using?
6.1

Any related open or closed issues to this bug report?

Screenshots:

Are you thinking about creating a pull request for this issue?

This issue might need more discussion, since it is related to the way how guestbooks are currently implemented;

• What should be the correct behavior for datasets with both open and restricted files?
• Would it make more sense to move the 'Guestbook Entry Option' from collection to dataset (or even file) level?

Start by reproducing the guestbook workflows described for open and restricted files, then trace the guestbook response creation and collection statistics paths. No source files or tests are named; done requires an agreed behavior for mismatched guestbook options and datasets, with no empty responses created when users are not prompted.