[Modified value] sometimes appears after switching between examples

Q&A (please complete the following information)

• OS: Windows 10
• Browser: Chrome 76
• Method of installation: https://editor.swagger.io
• Swagger-UI version: 3.23.4
• Swagger/OpenAPI version: OpenAPI 3.0

Content & configuration

Example Swagger/OpenAPI definition:

openapi: 3.0.0
info:
  title: test
  version: 1.0.0

paths:
  /foo:
    post:
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/MyModel'
            examples:
              '0':
                value:
                  message: test
              '1':
                value:
                  message: hello, world
          application/xml:
            schema:
              $ref: '#/components/schemas/MyModel'
      responses:
        '200':
          description: ok

components:
  schemas:
    MyModel:
      type: object
      properties:
        message:
          type: string
      xml:
        name: root

Describe the bug you're encountering

If the request body has several media types with examples, switching between those media types sometimes adds an extra [Modified value] item to the examples list. This happens outside the "try it out" mode.

To reproduce...

Steps to reproduce the behavior:

1. Go to https://editor.swagger.io and paste the example above.
2. Expand POST /foo.
3. From the "Examples" list, select the example 1.
4. Switch to application/xml. (Note the example is not updated to XML - this is issue #5460).
5. Switch back to application/json.
6. Open the "Examples" list.

Expected behavior

The example list should contain only "0" and "1" - i.e. the examples defined in the spec.

Actual behavior

The examples list contains "[Modified value]" even though we didn't modify anything. The "[Modified value]" example makes sense during "try it out" only.

Screenshots

Start at the Examples list in Swagger UI using the YAML definition and reproduction steps at editor.swagger.io. Switch between application/json and application/xml after selecting example 1, then inspect how the examples list changes outside "try it out" mode. Done means switching media types leaves only the spec-defined examples "0" and "1", without adding "[Modified value]".