There actually is.  The problem here is that this will pick up Multibindings as well as FactoryModuleBuilders that are installed in the bootstrap phase and this will result in duplicate bindings so that creating the injector will fail.  I'm almost inclined to require that all discoverable dependency modules implement a specific interface although I'm concerned that this would be too restrictive.  For now I think @Singleton, which is actually required to ensure duplicate dependent modules aren't instantiated, should work just fine.