Bug 476587

SUMMARY
When adding a DAV-Groupware-Resource (NextCloud), the process akondai_davgroupware_resource runs in circles, maxing out one CPU core. When then completing a task in Kalendar, the Kalendar GUI freezes.
Restarting the PC does not fix the problem.

STEPS TO REPRODUCE
1. Burger-Menu -> Setup -> Kalendar Setup -> Accounts -> Calendar -> Add -> Dav-Groupware-Resource
2. Enter Username/Password
3. Manual Setup
4. Add -> CalDav -> https://XXXXX/remote.php/dav
5. Finish setup
6. akondai_davgroupware_resource now runs in circles (100% CPU load on one core)
7. Check a task to complete it
8. Kalendar now freezes

OBSERVED RESULT
akondai_davgroupware_resource uses 100% of one CPU core. Kalendar frozen.

EXPECTED RESULT
Calendar events and tasks are syncronized. Checking tasks completes them.

SOFTWARE/OS VERSIONS
Linux: Gentoo Linux 2.14
KDE Plasma Version: 5.27.8
KDE Frameworks Version:  5.110.0
Qt Version: 5.15.10
Graphics: X11

ADDITIONAL INFORMATION
I have been using Kalendar to synchronize my tasks and calendar entries for half a year without issues.
About two weeks ago checking a task froze Kalendar. After killing and restarting Kalendar i realized that one CPU core was being eaten by akondai. After restarting the PC did not fix the issue i removed the synchronization and added it again, and here we are.
For now i am leaving Kalendar and NextCloud disconnected so my CPU does not run hot.