API Responses Add required: true to enforce content in a response

[R0bG]

In a similar fashion to the way that request bodies can set as mandatory with the required:true property it would be useful if this could be extended to response bodies.

 responses:
    '201':
      description: Messages created
      content: 
      **required: true** 
        application/json:
          schema:
              $ref: '#/components/schemas/StandardResponse'