If an event has a LAST-MODIFIED:
LAST-MODIFIED;VALUE=DATE-TIME:20190308T231001Z
this seems not to be recognized by InfCloud. As a result, when changing the
event via InfCloud, an additional LAST-MODIFIED is added:
LAST-MODIFIED:20190309T090207Z
...
LAST-MODIFIED;VALUE=DATE-TIME:20190308T231001Z
Other caldav systems, e.g. ownCloud, then reject this event as being
invalid.
I'm not quite sure who to blame...
-- Johan
