openHAB 3 System startup with warning

I use a openHAB 3 installation via openhabian.
I get a WARNING in the openhab.log when restarting the system:

2022-01-10 22:59:26.216 [WARN ] [mmon.WrappedScheduledExecutorService] - Scheduled runnable ended with an exception: 
java.lang.NullPointerException: null
	at org.openhab.binding.zigbee.ember.handler.EmberHandler.setGroupRegistration( ~[?:?]
	at org.openhab.binding.zigbee.ember.handler.EmberHandler.initializeDongleSpecific( ~[?:?]
	at org.openhab.binding.zigbee.handler.ZigBeeCoordinatorHandler.initialiseZigBee( ~[?:?]
	at org.openhab.binding.zigbee.handler.ZigBeeCoordinatorHandler.lambda$2( ~[?:?]
	at java.util.concurrent.Executors$ ~[?:?]
	at ~[?:?]
	at java.util.concurrent.ScheduledThreadPoolExecutor$ ~[?:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker( [?:?]
	at java.util.concurrent.ThreadPoolExecutor$ [?:?]
	at [?:?]

What is the reason?

It might well be a proper Zigbee issue you are facing; but if you have recently upgraded to OH3.2 and this is something popping up only at startup, this might be a variant of what is discussed here: