currenly groovy is in the default dependencies of the engine.
i think we should try to make that an optional dependency. maybe we can scan for availability of one of the groovy - jsr 223 engine classes and depending of the outcome add it to our ScriptingEngines.
alternatively we could consider to document how users have to add groovy (just like now we'll have to document how users can add any of the other scripting languages)
that will keep the minimal runtime dependencies even more neat and tidy. especially since we now have explicit groups of examples showing the runtime and testing dependencies explicit.
