[Bug]: Empty example object was emitted when the model contains a enum type property

[akishichinibu]

Describe the bug

The example for model AA is generated correctly; however, the example of Output becomes an empty object when set the type of property to the enum Types in model A. It seems that this issue will disappear when replacing the type enum with a string literal.

import "@typespec/http";
import "@typespec/rest";
import "@typespec/openapi";
import "@typespec/openapi3";

using TypeSpec.Http;
using TypeSpec.Rest;
using TypeSpec.OpenAPI;

enum Types {
  A: "a";
  B: "b";
}

@example(#{
  type: Types.A,
  a: "a",
})
model A {
  type: Types.A;
  a: string;
}

model B {
  type: Types.B;
  b: int64;
}

@oneOf
@discriminator("type")
union X {
  A;
  B;
}

@example(#{
  x: #{
    type: Types.B,
    b: 4,
  }
})
model Output {
  x: X
}

model AA {
  type: "aa";
  a: string;
}

model BB {
  type: "bb";
  b: int64;
}

@oneOf
@discriminator("type")
union XX {
  AA;
  BB;
}

@example(#{
  xx: #{
    type: "aa",
    a: "aa",
  }
})
model Output2 {
  xx: XX
}

Output:

    Output:
      type: object
      required:
        - x
      properties:
        x:
          $ref: '#/components/schemas/X'
      example:
        x: {}
    Output2:
      type: object
      required:
        - xx
      properties:
        xx:
          $ref: '#/components/schemas/XX'
      example:
        xx:
          type: aa
          a: aa

Reproduction

👇
https://typespec.io/playground?c=aW1wb3J0ICJAdHlwZXNwZWMvaHR0cCI7CtIZcmVzdNUZb3BlbmFwadwcMyI7Cgp1c2luZyBUeXBlU3BlYy5IdHRwO9AVUmVzdNEVT3BlbkFQSTsKCmVudW3FGHMgewogIEE6ICJhIjsKICBCOiAiYiI7Cn0KCkBleGFtcGxlKCPEI%2BQAijrGMy5BLAogIGHFNCwKfSkKbW9kZWwgQcVLzSjEUmE6IHN0cmluZ8VVxitC0StCxCtiOiBpbnQ2NMZ%2Fb25lT2YKQGRpc2NyaW1pbmF0b3IoIsQ1IikKdW5pb24gWMVIxWdC8wC0eDogxQjPa%2BQAvsVtNMQKfeoAwk91dHB1dMVUeDogWOoAsEHsANwiYeYBK%2FUA2ewA2iJi5AFK%2FwDX9QDX5wDY5gDZ9QDa8ADb5ACV5gDY5QGYxg3xANsyxVjEPVjkAN4%3D&e=%40typespec%2Fopenapi3&options=%7B%7D&version=0.60.x

Checklist

• Follow our Code of Conduct
• Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion.
• The provided reproduction is a minimal reproducible example of the bug.

[timotheeguerin]

Simplified repro

Seems to be a combination of using an enum property inside a union