Sign goal fails on projects with maven-plugin packaging

If you run jar:sign on a project with maven-plugin packaging, jarsigner is run with the argument '<build dir>/<projectname><version>.maven-plugin' instead of '<build dir>/<projectname><version>.jar'.

A workaround is to add the configuration: <jarPath>${project.build.directory}/${project.build.finalName}.jar</jarPath> which is not very elegant.