Otherwise, we get .jar files opened with archive managers instead of being able to run them, needing to open a terminal and run "java -jar file.jar"
The desktop file should contain the following:
Name=Run Jar file
Comment=Run selected Jar file
Exec=java -jar %U
Java packages in the Portage tree should come with their own launchers and desktop files, therefore we assume that this is meant for users whom wish to start a binary jar application they have downloaded separately from elsewhere. Therefore this would rather belong to sys-apps/baselayout-java since it doesn't use java-config functionality. Because of that, I have changed the bug summary.