openapi: 3.0.0
info:
  title: Simplest Link
  version: 1.0.1
paths:
  '/users/{username}':
    get: 
      parameters:
        - name: username
          in: path
          required: true
          schema:
            type: string
      responses:
        '200': 
          description: A representation of a user
          content: 
            application/json: 
              schema:
                type: object
                properties:
                  id: 
                    type: integer
                  firstname:
                    type: string
                  lastname:
                    type: string
              example:
                id: 243
                firstname: Reginald
                lastname: McDougall
          links:
            userPhotoLink:
              operationId: getPhoto
              parameters:
                userid: $response.body#/id
  '/users/{userid}/photo':
    get: 
      operationId: getPhoto
      parameters:
        - name: userid
          in: path
          required: true
          schema:
            type: integer
      responses:
        '200':
          description: A photo image
          content:
            image/jpeg: {}