GMX calendar creation not working very well #624
Description
Tests were breaking for GMX. Claude has been fighting with this for a while, but I will yank out all the changes and ensure the tests are run towards a well-known calendar rather than creating new calendars. It makes no sense having a lot of cruft in the code just to support one operation on one commercial aas-provider. I still leave this as an open issue in case with the information found. It may be that this issue is also relevant for other providers.
When doing MKCALENDAR, the calendar URL is given by the client. However, GMX wants to control the calendar URLs, so the calendar will pop up at another URL than what the client specified. That's the gist of the issue, I think.
Claude tried to fix this in commit 1a4f006 and commit 0171a7e - I will create a new issue branch to preserve those commits. Even with those commits in place, there were still troubles with GMX.