/usr/share/java/plexus-maven-plugin.jar is in libplexus-maven-plugin-java 1.3.8-7.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/java/../maven-repo/org/codehaus/plexus/plexus-maven-plugin/1.3.8/plexus-maven-plugin-1.3.8.jar