If your logs are full of warnings like these
Field 'firmwareStatus' could not be eliminated: Can not set final org.openhab.core.thing.firmware.dto.FirmwareStatusDTO field org.openhab.core.io.rest.core.thing.EnrichedThingDTO.firmwareStatus to null value
when you go to the settings in the UI, that’s my fault and a fix is on the way: [REST] Add firmwareStatus to things in summary mode by ghys · Pull Request #1932 · openhab/openhab-core · GitHub
If you’re so annoyed and can’t wait to get rid of these messages, do a
bundle:update org.openhab.core.io.rest.core https://github.com/ghys/openhab-core/releases/download/rc1-rest-fix/org.openhab.core.io.rest.core-3.0.0-SNAPSHOT.jar
(disclaimer: in theory you shouldn’t update untested bundles like this 
)