Gunnar Morling, Steve Ebersole As an alternative, do you think the implementations of MetadataBuilder could call some SPI sow e could alter the configuration, or is that against the philosophy? Another possible gotcha is that it might not be easy to discover these "integrator-like" integration components.
That does not solve your downcasting concern and would require some kind of unwrap method that the integrator bit would be able to react to.