Note: the logback-nexus.xml suggestion applies only to Nexus 2.x, specifically $INSTALL_DIR/sonatype-work/nexus/conf/logback-nexus.xml
As noted on How to override logback config in Nexus 3?, as of Nexus 3.15.2, the corresponding file for Nexus 3.x is not in the sonatype-work folder. Rather, it is in the nexus version folder $INSTALL_DIR/nexus-3.15.0-01/etc/logback/logback.xml