Any idea how to set the logs in the console to ECS format?

Our Keycloak runs in Docker container.
I tried using Quarkus Logging JSON.
I tried to set the ECS format as follows ENV QUARKUS_LOG_JSON_LOG_FORMAT=ecs
and also via ENTRYPOINT [..., "-Dquarkus.log.json.log-format=ecs"]
Does not help.

Then I tried using Log4j and Log4j2. Each separately. For each of them I set the correct log4j.xml and log4j2.xml file. Documentation is here.
None of that helped. Logs are still not in ECS format.

Has anyone ever tried it? How did you do?