If you're ok with using log4j2 APIs, there is also...

# announcements

[rocketraman]

If you're ok with using log4j2 APIs, there is also https://github.com/rocketraman/logging-log4j-kotlin which I started with the intent to upstream into log4j2 (https://issues.apache.org/jira/browse/LOG4J2-1705). The main thing missing is location-aware logging.