fix(subgraph): Preserve resolveReference fns during schema transforms

[trevor-scheer]

Currently resolveReference and resolveObject are special properties on GraphQLObjectTypes which don't obey the type system / public API. We should investigate moving these properties to the extensions object so they are preserved through normal usage of the public API (i.e. calling toConfig() on the object.

Ref: ardatan/graphql-tools#2687

[glasser]

@martijnwalraven pointed out in ardatan/graphql-tools#2857 (comment) that this would be a backwards-incompatible change, but I suspect it is fine to make it (and bump the 0.x version). If for some reason that's not ok, we could put the fields on both places and just document the old way as deprecated and not preserved by things like mapSchema.

We should consider taking the advice on the doc comment on graphql-js GraphQLObjectTypeExtensions and put these functions not directly on extensions but on an object like extensions.apolloSubgraph, for later extensibility.

[trevor-scheer]

I haven't validated the workaround myself, but I figure it's worth sharing if anyone finds themselves running into this issue - could be worth a shot.

https://community.apollographql.com/t/are-object-resolvers-broken-with-custom-schema-directives/1578/3

Thanks to @vad3x for providing it.

[vad3x]

Hi @trevor-scheer, any updates?

[trevor-scheer]

@vad3x no update yet. This is one of those things I'd love to get to, but no idea when. Open to assisting with a PR though!