As openHAB 4 is now released, it would be nice if some users could test this Pull request (built binary for openHAB 4 linked there, take the version 4.1.0-SNAPSHOT).
Just make sure to uninstall a previously installed version. And please do a backup to be sure, as things will be upgraded and there is no other way back.
As things have been changed, please check out the updated readme: https://github.com/daMihe/openhab-addons/blob/13649-extract-liveevent-tagexecutor/bundles/org.openhab.binding.icalendar/README.md
Thanks to @RRoe for already doing a first test. Please report bugs or findings directly in the PR. This topic is more for discussion.