Allow $ref in request body and response content objects

[DavidBiesack]

I'd like to define an API to allow the client to accept either application/json or application/problem+json for responses; they share the same schema and description. At present, I must copy/paste the Media Type Object each time, rather than define it oncereuse one

That is, I must code:

        '400':
          description: Bad Request
          content:
            application/json:
              description: {My description of the response}
              schema:
                $ref: '#/components/schemas/problemResponse'
            application/problem+json:
              description: {My description of the response}
              schema:
                $ref: '#/components/schemas/problemResponse'

when I'd really like to do is

        '400':
          description: Bad Request
          content:
            application/json:
              description: {My description of the response}
              schema:
                $ref: '#/components/schemas/problemResponse'
            application/problem+json:
               $ref: '#../application~1json'

Maintaining copies is not scalable, especially if one uses Specification Extensions inside the media type object

Each operation's 400 response (or each 422 response, etc) may differ (error descriptions change) so using a $ref for the entire Response Object is not a complete solution.