I think must be cleared when should be strictly necessary that Nautilus should default to Java or to File Roller.
In my opinion:
1) If Java is not installed into the system than a .jar cuold be defaulted to a switcher proxy that ask to download Java to run the jar or to open it with File Roller
2) I Java is installed on the system, Nautilus should default the jar against java because a .jar is primary an application to run and that a package from the "Java world" point of view.
I think must be cleared when should be strictly necessary that Nautilus should default to Java or to File Roller.
In my opinion:
1) If Java is not installed into the system than a .jar cuold be defaulted to a switcher proxy that ask to download Java to run the jar or to open it with File Roller
2) I Java is installed on the system, Nautilus should default the jar against java because a .jar is primary an application to run and that a package from the "Java world" point of view.