/usr/share/java/cobertura-maven-plugin-2.3.jar is in libmaven-cobertura-plugin-java 2.3+dfsg-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/java/../maven-repo/org/codehaus/mojo/cobertura-maven-plugin/2.3/cobertura-maven-plugin-2.3.jar