Models using allOf break when deeply nested by $ref

Q&A (please complete the following information)

• OS: Ubuntu
• Browser: Chrome
• Version: 92
• Method of installation: editor.swagger.io
• Swagger-UI version: 3.51.1
• Swagger/OpenAPI version: OpenAPI 3.0

Content & configuration

Example Swagger/OpenAPI definition:

openapi: 3.0.0
info:
  title: Test REST API
  version: 1.0.0
components:
  schemas:
    TheOneWhichBreaks:
      allOf:
        - type: object
          properties:
            id:
              type: string
        - type: object
          properties:
            position:
              type: integer
    ReferringA:
      type: object
      properties:
        theOneWhichBreaks:
          $ref: "#/components/schemas/TheOneWhichBreaks"
    ReferringB:
      type: object
      properties:
        referringA:
          $ref: "#/components/schemas/ReferringA"
    HereBreaksToo:
      type: object
      properties:
        referringB:
          $ref: "#/components/schemas/ReferringB"
paths:
  /works:
    get:
      tags:
        - Test
      summary: Shown as intended
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                type: object
                properties:
                  referringA:
                    $ref: "#/components/schemas/ReferringA"
  /breaks:
    get:
      tags:
        - Test
      summary: Isn't shown as intended
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                type: object
                properties:
                  referringB:
                    $ref: "#/components/schemas/ReferringB"

Describe the bug you're encountering

A model combining other models with allOf doesn't show properly if there are 3 or more $ref usages on higher levels. In this case it usually has a value "string" or empty object.

To reproduce...

Steps to reproduce the behavior:

1. Go to editor.swagger.io
2. Paste the definition I left above
3. Compare responses of two paths. Notice how TheOneWhichBrakes model shows
4. You also can check a model called "HereBreaksToo"

Expected behavior

Referenced models should render their type despite of referencing depth.

Screenshots

Additional context or thoughts

I've managed to reproduce the bug using different environments:

swagger-ui-express

swagger-ui-express@4.1.6
swagger-ui-dist@3.51.1

WebStorm

Plugin OpenAPI Specifications 202.7319.8

editor.swagger.io

There is a feature here. It reproduces during the first render. But there is an algorithm which makes it display properly:

1. Expand the /works path. It always shows TheOneWhichBrakes model properly. You also can just expand TheOneWhichBrakes model itself
2. Expand the /breaks path. It will show you the broken view
3. Make a meaningless change in the editor. You can add an extra line in the end of the definition
4. See how /breaks is rendered as intended now

Start in editor.swagger.io with the supplied OpenAPI definition and compare the /works and /breaks responses, including the HereBreaksToo model. Reproduce the first-render failure and confirm that deeply referenced allOf models render their types consistently after the fix.