[Bug]: (CalDAV) Calendar event cancellation iMip messages are sent twice, on delete and on trash empty

[SebastianKrupinski]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

Calendar iMip messages are sent twice, once when the event is deleted and once when the trash is emptied

Steps to reproduce

1. Create Event (In the future) with attendee (has email address)
2. Delete Event with attendee
3. Empty trash bin

Expected behavior

Calendar iMip message should only be sent once on delete

Installation method

None

Nextcloud Server version

master

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.3

Web server

Nginx

Database engine version

MySQL

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

N/A

List of activated Apps

N/A

Nextcloud Signing status

N/A

Nextcloud Logs

N/A

Additional info

No response

[SebastianKrupinski]

Tested with single and multiple attendees and external email client

Created Event Message

Deleted Event Message

Trash Empty Message

[SebastianKrupinski]

Possible solution.

Add check to determine if message was deleted or trash was emptied in iMipPlugin Schedule function.

server/apps/dav/lib/CalDAV/Schedule/IMipPlugin.php

Line 106 in 94bc020

public function schedule(Message $iTipMessage) {