/usr/share/java/maven-site-plugin-2.1.jar is in libmaven-site-plugin-java 2.1-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/java/../maven-repo/org/apache/maven/plugins/maven-site-plugin/2.1/maven-site-plugin-2.1.jar