--xmvn-debug option of %mvn_build enables XMvn debug output by configuring slf4j-simple logging sink - it sets org.slf4j.simpleLogger.log.org.fedoraproject.xmvn property to debug. Since Maven 3.4.0, a different logging backend is used, which doesn't recognize this property.
--xmvn-debug
option of%mvn_build
enables XMvn debug output by configuringslf4j-simple
logging sink - it setsorg.slf4j.simpleLogger.log.org.fedoraproject.xmvn
property todebug
. Since Maven 3.4.0, a different logging backend is used, which doesn't recognize this property.