How to reference a parameter for one dynamic list from another

Question

Hello,

I'm writing a custom connector with a trigger. The trigger uses two parameters with dynamic lists, with one parameter depending on the other. Let's imagine it's a connector to be triggered by new comments to a blog post. First you have to select the blog, and than select the post from that blog.
I've managed to implement this when the parameters are at the root of the body. However, in our backend these must be nested.

Here's the trigger definition:

/api/trigger/subscriptions/BlogCommentPublished:
x-ms-notification-content:
  description: Trigger Payload
  schema: {$ref: '#/definitions/BlogCommentModel'}
post:
  summary: A new comment to a blog post was published
  operationId: blog-comment-published
  consumes: [application/json]
  parameters:
  - in: body
    name: body
    description: Trigger Request Body
    schema:
      required: [config, filterlist]
      type: object
      properties:
        config:
          required: [url, connectorName]
          type: object
          properties:
            url: {title: callback Url,
              description: callback Url, type: string, x-ms-notification-url: true, x-ms-visibility: internal}
            connectorName: {title: Connector Name, description: Connector Name,
              default: BlogPostConnector, type: string, x-ms-visibility: internal}
        filterlist:
          required: [blogId, postId]
          type: object
          properties:
            blogId:
              title: Blog
              description: The blog to monitor
              type: string
              x-ms-dynamic-values:
                operationId: load-blogs
                value-path: Id
                value-title: Name
                parameters:
                  callbackType: syncHttp
                  connectorName: BlogPostConnector
            postId:
              title: Tag
              description: The post to monitor
              type: string
              x-ms-dynamic-values:
                operationId: load-posts
                value-path: Id
                value-title: Name
                parameters:
                  callbackType: syncHttp
                  connectorName: BlogPostConnector
                  accountId:
                    parameter: blogId
  responses:
    '201': {description: Created}
  x-ms-trigger: single

You see, the load-posts action requires the blogId. It works when blogId and postId are properties of the root "body" object. However, you see that blogId and postId are properties of filterlist, which in turn is a property of the root object.

I guess that the paremeter reference (accountId: { parameter: blogId } near the end) is wrong, but I tried different ways like

• accountId: { parameter: blogId }
• accountId: { parameterReference: blogId }
• accountId: { parameter: filterlist/blogId }

but I never got it working. What's the proper way to reference one parameter from another in a nested object?