RFC: Private visibility on MetadataFactory

[dominics]

Would you consider merging a PR that increased the visibility of a few parts of MetadataFactory from private to protected? (It wouldn't necessary have to become part of the stable API - but allowing overriding of parts of the MetadataFactory will prevent me having to copy/paste large parts of it.)

My use case:

• I'm trying to prevent a few round trips to the cache caused by a very 'deep' hierarchy of classes, all of which I know will have no metadata (the cache checks are unnecessary)
• There's nothing overridable in the MetadataFactory that will allow me to short-circuit before the call to check the cache

I've looked into:

• Adjusting the 'hierarchy' metadata class via constructor parameter
  • This class seems to just hold the results, and won't allow me to filter before incurring the cost of the cache round-trips
• "Preloading" null metadata entries into the 'loadedMetadata' member array of the factory
  • This would allow the parent classes to be excluded without going to the cache, but the member array is private
• Overriding getClassHierarchy(), which is probably closest to what I actually want to do
  • This would allow me to filter the hierarchy to the classes I care about, but getClassHierarchy() is private, so this requires copy/paste of about 60 lines - yuck

I can't seem to find a way around this, but if you have an alternative to suggest, I'd be happy to hear it. The long-term fix if you don't want to open up the internal API might be to use a strategy pattern for turning the class name into a hierarchy, so that I can override that part via DI.