Problem with Log4j in Docker image 'universalrobots/ursim_e-series'

When I run the simulator docker image ( it reports missing Log4j files:

ERROR StatusLogger Log4j2 could not find a logging implementation. Please add log4j-core to the classpath. Using SimpleLogger to log to the console…

I can see there are multiple logging related files in the docker image, but apparently they are somehow not in the classpath:


That is probably why my “LOGGER.warn” messages are not printed (whereas System.out.println is printed).

Please advice how I can enable Log4j?