see https export const swaggerYaml_3_0 = `\
openapi: 3.0.0
info:
  title: Callback Example
  version: 1.0.0
paths:
  /streams:
    post:
      description: subscribes a client to receive out-of-band data
      parameters:
        - name: callbackUrl
          in: query
          required: true
          description: |
            the location where data will be sent.  Must be network accessible
            by the source server
          schema:
            type: string
            format: uri
            example: https://tonys-server.com
      responses:
        '201':
          description: subscription successfully created
          content:
            application/json:
              schema:
                description: subscription information
                required:
                  - subscriptionId
                properties:
                  subscriptionId:
                    description: this unique identifier allows management of the subscription
                    type: string
                    example: 2531329f-fb09-4ef7-887e-84e648214436
      callbacks:
        # the name \`onData\` is a convenience locator
        onData:
          # when data is sent, it will be sent to the \`callbackUrl\` provided
          # when making the subscription PLUS the suffix \`/data\`
          '{$request.query.callbackUrl}/data':
            post:
              requestBody:
                description: subscription payload
                content:
                  application/json:
                    schema:
                      properties:
                        timestamp:
                          type: string
                          format: date-time
                        userData:
                          type: string
              responses:
                '202':
                  description: |
                    Your server implementation should return this HTTP status code
                    if the data was received successfully
                '204':
                  description: |
                    Your server should return this HTTP status code if no longer interested
                    in further updates
` ;