event in editable shared calendar with visibility "busy" looses data when updated by a user shared to

[simonbuehler]

Steps to reproduce

1. user a shares calendar writable to user b, creates event "doctor" with visibility "busy"
2. user b sees event with title "busy"
3. any updates user b does do destroy the original title, content or location

Expected behaviour

events with visibility "busy" should not be editable in a shared calendar

Actual behaviour

title can be overwritten with "busy"and location/description become empty

Server configuration

PHP version: 7

Nextcloud version: 14

[nextcloud-bot]

GitMate.io thinks possibly related issues are #11214 (Share calendar to users or groups with "show only as busy".), #4880 (Calendars invitations for event in shared calendars), #3830 (No calendar invitation send for event in shared calendars ), #6741 (calendar sharing with user who has his displayname set leads to error), and #2865 (Users can't grant other users "edit" function for shared calendars).

[maksemuz]

Expected behaviour

events with visibility "busy" should not be editable in a shared calendar

I'd prefer such events should be shown as public for editors and as "only busy" for readonly users.

[georgehrke]

Duplicate of #5551