Do not resolve $ref in OAS 2.0 response examples

[hkosova]

Q&A (please complete the following information)

• OS: Windows 7
• Browser: Chrome latest
• Method of installation: http://editor.swagger.io
• Swagger-UI version: 3.17.5
• Swagger/OpenAPI version: 2.0

This issue was originally reported on Stack Overflow: https://stackoverflow.com/questions/51095684/ref-in-response-example

A similar issue for OAS 3.0 was reported in #4564 and fixed in swagger-api/swagger-js#1349.

Describe the bug you're encountering

From what I understand, OAS 2.0 response examples (responses.<code>.examples.<media-type>) are inline examples and do not support $ref. But Swagger UI tries to resolve properties named $ref in these examples.

Swagger/OpenAPI definition

swagger: '2.0'
info:
  title: test
  version: 0.0.0
paths:
  /:
    get:
      responses:
        200:
          description: OK
          examples:
            application/json:
              status: ok
              $ref: '#/definitions/Foo'

Actual behavior

Response example is displayed as

{
  "status": "ok"
}

Expected behavior

Response example is displayed as

{
  "status": "ok",
  "$ref": "#/definitions/Foo"
}