Enum with null entry triggers "too much recursion" error

[wking]

If I point swagger-ui v2.1.0 at the following spec:

{
  "swagger": "2.0",
  "definitions": {
    "pet": {
      "type": "object",
      "properties": {
        "species": {
          "type": "string",
          "enum": [
            null,
            "cat",
            "dog"
          ]
        }
      }
    }
  }
}

I get a too much recursion error pointing at resolveAllOf. The JSON Schema spec says for enums:

Elements in the array MAY be of any type, including null.

[webron]

null is not a valid value in Swagger. We don't support full JSON Schema. Please follow OAI/OpenAPI-Specification#229.

[wking]

On Thu, Jun 25, 2015 at 09:56:07AM -0700, Ron wrote:

null is not a valid value in Swagger. We don't support full JSON
Schema. Please follow
OAI/OpenAPI-Specification#229.

I'm clear on this for Swagger 2.0 now, and I just submitted #508 here
to make it easier for other folks to find this information. Between
OAI/OpenAPI-Specification#229 and #508, I think this is closable.