Doesn't that create a fair amount ambiquity? What if I have a service and and a class with the same name?

I'll have to change this comment though, since it's not really a PHP callable I expect. It also accepts a ``Reference`` or ``Definition`` and a method name as an array.

That said, if we allow a plain service name instead of a reference we'll break the inlining and get the weird bug with private services again. The only solution to that would be to do the conversion at parse time - but than I don't know all the services and get back to the problem above.