AddModuleInfoMojo attempts to add module-info to the JAR at buildDirectory.toPath().resolve( artifactId + "-" + version + ".jar" );. This assumes the value of ${project.build.finalName} and is very often not correct.
Please use ${project.build.finalName} instead. It also assumes that this artifact is found in ${project.build.directory} regardless of the value of outputDirectory supplied to the maven-jar-plugin. This path should be exposed as a configuration parameter.