### Steps to reproduce

* fetch a file info response from `/ocs/v1.php/apps/integration_openproject/fileinfo/:id`


### What is the buggy behavior

* modifier and owner is not stable

* for files uploaded AND modified, it has a value

* for files only uploaded modifier is `null`

* for files seeded modifier is equal to owner

* owner is not creator

* e.g. in a file uploaded to a shared folder owner of the file is not the uploader, but the owner of the folder

* modifier is null, so we can't rely on any data here to get the last interaction (upload)


### What is the expected behavior?

* ~~modifier always shows the user, that did the last interaction on a file~~

* modifier always shows the user who did the last interaction on a file, if the `activity` app is enabled Begin of the insertion


### Testing Steps:

1. Setup the integration (any method)

2. Enable activity app in Nextcloud

3. Upload file to/from OpenProject work-package

4. Check the user avatar in the uploaded file - might need to reload the page
<img class="image_resized op-uc-image op-uc-image_inline" style="width:236px;" src="/api/v3/attachments/783596/content">End of the insertion