No airquality addon in OH4

In openhab 3 I used the airquality addon. According to the documentation (Air Quality - Bindings | openHAB) it should also be available for version 4. It cannot be selected in the interface. Manual installation via the service file doesn’t work either.
What am I doing wrong?

René

I found the solution. First clear cache and reinstall addonn. In version 4, thing became a combination of bridge and thing.