"Execute" doesn't work for input model with optional nested object

[WinniX]

Q&A

• OS: Windows
• Browser: chrome
• Version: 89.0.4389.128
• Swagger-UI version: https://editor.swagger.io/
• Swagger/OpenAPI version: Swagger 2.0

Content & configuration

Example Swagger/OpenAPI definition:

swagger: '2.0'
info:
  title: swashbuckletest
  version: v1
paths:
  /WeatherForecast:
    put:
      tags:
        - WeatherForecast
      consumes:
        - application/json
        - text/json
        - application/*+json
      parameters:
        - in: body
          name: body
          schema:
            $ref: '#/definitions/TopModel'
      responses:
        '200':
          description: Success
definitions:
  NestedModel:
    required:
      - id
    type: object
    properties:
      id:
        type: string
  TopModel:
    type: object
    properties:
      nested:
        $ref: '#/definitions/NestedModel'

Swagger-UI configuration options:

app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "swashbuckletest v1"));

Describe the bug you're encountering

PUT endpoint uses "TopModel" as input model and inside it there is an optional "nested" field of type "NestedModel".
"nested" object has a required "Id" field. Swagger UI doesn't allow to execute the request without "nested" field.

To reproduce...

Steps to reproduce the behavior:

1. Go to https://editor.swagger.io/
2. Click on 'File' -> 'Import file' and pick the YAML (see above)
3. Expand PUT ​/WeatherForecast, click 'Try out'
4. Replace 'body' with {} (empty object)
5. Click 'Execute' button - no request were made

Expected behavior

In previous versions we could have omitted an optional object. So the body input {} should be considered as valid in this case.

[hkosova]

Possibly the same issue as #7086.