Is it possible to declare a custom response header which would be present in all responses without copying it in each of the response structure?
According to section 2.3 Response’s headers of Writing OpenAPI (Swagger) Specification Tutorial – Part 5 – Advanced Input And Output Modeling the answer is no. Which is what I understand from the 2.0 spec too.
Vote/comment on Structural improvements: enhance headers handling · Issue #690 · OAI/OpenAPI-Specification.