JSON Patch request body should use content-type application/json-patch+json

[mikekistler]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

A patch operation that accepts a JsonPatchDocument<T> that was added as part of the JSON Patch with System.Text.Json feature in .NET 10 preview 4 is shown in the generated OpenAPI document as accepting the media type "application/json". According to RFC 6902, the media type should be "application/json-patch+json".

Expected Behavior

A patch operation that accepts a JsonPatchDocument<T> should have a request body with media type "application/json-patch+json" in the generated OpenAPI document.

Steps To Reproduce

A minimal repro for this problem is in the "json-patch-media-type" directory of this repo:

https://github.com/mikekistler/dotnet10-issue-repros

Exceptions (if any)

No response

.NET Version

10.0.100-preview.4.25258.110

Implementation Plan

The JsonPatchDocument type should implement the IEndpointParameterMetadataProvider interface and add the appropriate AcceptsMetadata with the "application/json-patch+json" content-type. Test coverage should be added to assert the correct behavior of the type when used in an OpenAPI document by adding an endpoint that takes a JsonPatchDocument to this test file (https://github.com/dotnet/aspnetcore/blob/c5d6996bd22e916b04aa792185b2fd2214ae22fe/src/OpenApi/sample/Endpoints/MapSchemasEndpoints.cs) and updating the snapshot tests.

[mikekistler]

@captainsafia If we choose not to fix this in .NET 10, will it be considered a breaking change if we fix it in .NET 11 or later?

[martincostello]

I picked up where Copilot got to, fixed it up and opened #62988 to make this change (correctly I hope...).