From live discussion with @toumorokoshi / @earth2marsh / @makahmad:

• We need a unified version of the oneof concept.
• @toumorokoshi and I agree that the protobuf approach is preferable because clients can easily determine which case is being used.
• @earth2marsh suggests that at some point OAS Moonwalk may support non-JSON Schema modeling/schema languages.

Conclusion: leave this as-is and file an issue to create an AEP on oneofs defining what they mean and how to implement them in both protobuf and OAS. Link it here.

Originally posted by @rofrankel in #194 (comment)