Background and Motivation

When the OpenAPI extension methods were added in RC1, they were added in the Mvc.Core assembly under the Microsoft.AspNetCore.Http namespace like so:

namespace Microsoft.AspNetCore.Http
{
    public static class OpenApiDelegateEndpointConventionBuilderExtensions
    {
        ...

        public static DelegateEndpointConventionBuilder ExcludeFromDescription(this DelegateEndpointConventionBuilder builder)

        ...
    }
}

For RC2, we want to move these extension methods to the Routing assembly since they are designed to be used with the DelegateEndpointConventionBuilder. The types will stay in the same namespace. Functionally, the user won't have to change anything in their code but this change will set us up for success moving forward with regard to making trimming of minimal apps a lot easier.

Proposed API

To support this change, some new types had to be added to support the relocation of the API.

First, the MediaTypeCollection type is being moved to the Microsoft.AspNetCore.Http assembly. The type is still in the same namespace.

This PR introduces a new IProducesTypeMetadata to the Microsoft.AspNetCore.Http.Metadata namespace

// Assembly: Microsoft.AspNetCore.Http
namespace Microsoft.AspNetCore.Http.Metadata
{
    public interface IProducesResponseTypeMetadata
    {
        Type? Type { get; }

        int StatusCode { get; }

        void SetContentTypes(MediaTypeCollection contentTypes);
    }
}

Usage Examples

The IProducesResponseTypeMetadata is designed to be used as the implementing interface for the ProducesResponseTypeAttributes like so:

internal class ProducesResponseTypeAttribute : IProducesResponseTypeMetadata

Fixes #35905