OpenAPI - Polymorphism class does not work for response

[mickaelropars]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I have a method that produce
and I am using the Microsoft.AspNetCore.OpenApi package in order to produce the openapi json file

here is my code

[ProducesResponseType(typeof(ConcreteClass1),StatusCodes.Status200OK)]
[ProducesResponseType(typeof(ConcreteClass2), StatusCodes.Status200OK)]
[ProducesResponseType(typeof(ConcreteClass3), StatusCodes.Status200OK)]
public ActionResult<BaseClass> Get(int id)
{
    var dto= service.Get(id);
    return Ok(dto);
}

The tree ConcreteClass implement the same BaseClass

But in the json produce openAI only ConcreteClass3 is present

Expected Behavior

what I am expecting is in the OpenApiOperation Response to have the 3 schemas described using the "oneOf" properties in order to store the 3 schemas

Steps To Reproduce

[ProducesResponseType(typeof(ConcreteClass1),StatusCodes.Status200OK)]
[ProducesResponseType(typeof(ConcreteClass2), StatusCodes.Status200OK)]
[ProducesResponseType(typeof(ConcreteClass3), StatusCodes.Status200OK)]
public ActionResult<BaseClass> Get(int id)
{
    var dto= service.Get(id);
    return Ok(dto);
}

Exceptions (if any)

No response

.NET Version

9.0

Anything else?

No response