Logger not properly set up

[tillwenke]

getting

log4j:WARN No appenders could be found for logger (com.github.mauricioaniche.ck.CK).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

when building from mvnw for the first time. did not set up a logger intentionally so far.
Seems to be related to having no log4j.properties specified and https://logging.apache.org/log4j/1.2/faq.html#noconfig