openapi: 3.0.0
info:
  version: 1.0.0
  title: test
  description: example with callback
paths:
  /subscribe:
    post:
      summary: Subscribe to a webhook
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                callbackUrl:
                  type: string
                  format: uri
                  example: https://myserver.com/send/callback/here
              required:
                - callbackUrl
      callbacks:
        myEvent:
          '{$request.body#/callbackUrl}':
            post:
              requestBody:
                required: true
                content:
                  application/json:
                    schema:
                      type: object
                      properties:
                        message:
                          type: string
                          example: Some event happened
                      required:
                        - message
              responses:
                '200':
                  description: Your server returns this code if it accepts the callback
      responses:
        '201':
          description: Webhook created