Incorrect oneOf rendering in Swagger UI for OpenAPI 3.1.0

[tkramarczyk-vgw]

Q&A (please complete the following information)

• OS: [macOS]
• Browser: [chrome]
• Version: [online](https://editor.swagger.io/, https://editor-next.swagger.io/ )]
• Method of installation: [^^]
• Swagger-UI version: [^^]
• Swagger/OpenAPI version: [OpenAPI 3.1.0]

Content & configuration

I’m generating my OpenAPI specification using SpringDoc for my Kotlin project.

I’ve noticed that when I set the OpenAPI version to 3.0.x, Swagger UI renders my responses correctly. However, with the default version 3.1.0, it does not. The differences between the 3.0.x and 3.1.x specifications are minimal, so I believe this is an issue with Swagger UI.

To verify, I also tested the 3.1.0 specification with ReDoc, and it rendered correctly.

Swagger/OpenAPI definition:

openapi: 3.1.0
info:
  title: Example
  version: 1.0.0
paths: {}
components:
  schemas:
    Mercedes:
      allOf:
        - $ref: '#/components/schemas/Car'
        - type: object
          properties:
            foo:
              type: string
      required:
        - foo
        - name
        - type
    Bmw:
      allOf:
        - $ref: '#/components/schemas/Car'
        - type: object
          properties:
            bar:
              type: string
      required:
        - name
        - type
    Car:
      type: object
      discriminator:
        propertyName: type
      required:
        - name
        - type
      properties:
        type:
          type: string
          description: Type discriminator
        name:
          type: string
    MyResponse:
      type: object
      properties:
        cars:
          type: array
          items:
            oneOf:
              - $ref: '#/components/schemas/Mercedes'
              - $ref: '#/components/schemas/Bmw'
      required:
        - cars

Describe the bug you're encountering

This is what I get in swagger UI:

To reproduce...

Paste the yaml to https://editor.swagger.io/ or https://editor-next.swagger.io/

Expected behavior

3.1.0 vs 3.0.0

[gmli]

I’m having this error too, it’s quite frustrating because it makes Swagger-UI almost useless in OpenAPI 3.1.x

Here is a minimal definition to reproduce the issue : 

openapi: 3.1.0
info:
  title: Test
  description: ''
  license:
    name: ''
  version: 0.1.0
paths:
  /fetch:
    get:
      description: ''
      operationId: fetch
      responses:
        '200':
          description: ''
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/model'
components:
  schemas:
    model:
      type: object
      description: ''
      required:
        - id
      properties:
        id:
          type: string