Nashorn modules jdk.scripting.nashorn, jdk.scripting.nashorn.shell should be set with "main class".

Apart from being a convenience to run nashorn modules, this main class setting is needed because nashorn does not yet directly support user created modules (modular jars or directories for example). jjs tool does not have --module-path/-mp option. Only non-modular user classes and platform modules can be scripted with jjs -classpath/-cp option.

User can run java launcher with "-m jdk.scripting.nashorn.shell" and other options like --module-path/-mp option and script user-defined modules.