I am having difficulty specifying an XML example for a response in OpenAPI 3

I have a JSON file for OpenAPI 3 that contains the following:

            "trait_hasProjectResponse_200": {
                "description": "",
                "content": {
                    "application/xml": {
                        "example": {
                            "value" : "<project><foo>1</foo><bar>2</bar></project>"
                        }
                    }
                }
            },

This results in the following display on the current swagger-ui:

How do I specify an example of XML for a parameter or response in the OpenAPI 3 spec? I have looked through the documentation and it seems to be targest mostly at JSON. What do I need to do the my output that is generating the OpenAPI 3 JSON file.

I have also tried to use the externalValue and have has similar difficulties.

Remove the value key from the example (value is only used with multiple examples).

"example": "<project><foo>1</foo><bar>2</bar></project>"

Alternatively, you can define a schema for the response, and Swagger UI will generate examples based on the schema. In your example, the schema is a project object that contains the foo array. You can specify [1, 2] as the example values for the foo array:

  "components": {
    "responses": {
      "trait_hasProjectResponse_200": {
        "description": "",
        "content": {
          "application/xml": {
            "schema": {
              "$ref": "#/components/schemas/project"
            }
          }
        }
      }
    },
    "schemas": {
      "project": {
        "type": "object",
        "properties": {
          "foo": {
            "type": "array",
            "items": {
              "type": "integer"
            },
            "xml": {
              "wrapped": false
            },
            "example": [1, 2]
          }
        }
      }
    }
  }

This will give you: