Extract from https://github.com/OAI/OpenAPI-Specification/blob/9d7cf5c97a6a21b16f59ada/examples/v2.0/yaml/api-with-examples.yaml#L16

api-with-json-examples.yml

# https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#exampleObject
responses:
  "200":
    description: |-
      200 300 response
    examples:
      application/json: |-
        {
          "versions": [
              {
                "status": "CURRENT",
                "updated": "2011-01-21T11:33:21Z",
                "id": "v2.0",
                "links": [
                    {
                      "href": "http://127.0.0.1:8774/v2/",
                      "rel": "self"
                    }
                ]
              },
              {
                "status": "EXPERIMENTAL",
                "updated": "2013-07-23T11:33:21Z",
                "id": "v3.0",
                "links": [
                    {
                      "href": "http://127.0.0.1:8774/v3/",
                      "rel": "self"
                    }
                ]
              }
          ]
        }

api-with-yaml-example-states.yml

# Note this `x-request` and `x-response` doesn't exist yet
responses:
  "200":
    description: |-
      200 300 response
    examples:
      x-request:
        application/json:
          filter: all
      x-response:
        application/json:
          versions: 
            - status: "CURRENT"
              updated: "2011-01-21T11:33:21Z"
              id: "v2.0"
              links: 
                - href: "http://127.0.0.1:8774/v2/"
                  rel: "self"
            - status: "EXPERIMENTAL"
              updated: "2013-07-23T11:33:21Z"
              id: "v3.0"
              links: 
                - href: "http://127.0.0.1:8774/v3/"
                  rel: "self"

api-with-yaml-examples.yml

# https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#exampleObject
# Problems with this approach
#  * doesn't cover the request params
#  * doesn't support provider states / requests-reponse workflows
responses:
  "200":
    description: |-
      200 300 response
    examples:
      application/json:
        versions: 
          - status: "CURRENT"
            updated: "2011-01-21T11:33:21Z"
            id: "v2.0"
            links: 
              - href: "http://127.0.0.1:8774/v2/"
                rel: "self"
          - status: "EXPERIMENTAL"
            updated: "2013-07-23T11:33:21Z"
            id: "v3.0"
            links: 
              - href: "http://127.0.0.1:8774/v3/"
                rel: "self"