Multipart request doc example for OpenAPI 3.0 fails with err "not of type 'object' - 'address'"

Using Python3.8, flask 1.1.4, connexion 2.9.0 and swagger-ui-bundle 0.0.9 I cannot make the example work from https://swagger.io/docs/specification/describing-request-body/multipart-requests/ and I pasted that spec below. Please forgive if this is a dupe, I searched other open issues for multipart but didn't spot an exact match to this behavior.

Q&A (please complete the following information)

• OS: macOS
• Browser: Firefox
• Version: 91.1.0
• Method of installation: Python pip3, virtual environment
• Swagger-UI version: OAS3 (where is the exact version shown?)
• Swagger/OpenAPI version: OpenAPI 3.0

Content & configuration

Example Swagger/OpenAPI definition -- exactly the spec from the Swagger web site, URL above

    requestBody:
      content: 
        multipart/form-data: # Media type
          schema:            # Request payload
            type: object
            properties:      # Request parts
              id:            # Part 1 (string value)
                type: string
                format: uuid
              address:       # Part2 (object)
                type: object
                properties:
                  street:
                    type: string
                  city:
                    type: string
              profileImage:  # Part 3 (an image)
                type: string
                format: binary

Swagger-UI configuration options: (none)

Describe the bug you're encountering

The multipart form is not uploaded as I expect. I click "Try it out" in the UI, put in valid data. The window shows this cURL command:

curl -X 'POST' \
  'http://localhost:5000/api/v1/request_file' \
  -H 'accept: application/json' \
  -H 'Content-Type: multipart/form-data' \
  -F 'address={
  "city": "string",
  "street": "string"
}' \
  -F 'id=abc' \
  -F 'profileImage=@my-req-1.txt;type=text/plain'

But an error comes back:

{
  "detail": "'{\\r\\n  \"city\": \"string\",\\r\\n  \"street\": \"string\"\\r\\n}' is not of type 'object' - 'address'",
  "status": 400,
  "title": "Bad Request",
  "type": "about:blank"
}

The server logs this error:

2021-10-18T15:10:06-0400 ERROR connexion.decorators.validation http://localhost:5000/api/v1/request_file validation error: '{\r\n  "city": "string",\r\n  "street": "string"\r\n}' is not of type 'object' - 'address'

To reproduce...

Steps to reproduce the behavior:

1. Start the server
2. Go to the endpoint with this content model
3. Click on Try it out
4. Browse to a file for upload; leave the suggested string-parameter values
5. Click execute
6. See the error in the response window area

Expected behavior

I was hoping the documentation example would work :)

Start at Swagger UI's Try it out form and reproduce the issue with the OpenAPI 3.0 multipart schema from the linked documentation example. Compare the generated cURL request and the server's validation error for the nested address field. Done means the documented multipart example submits successfully without the address type error.