Issue when using AddApiExplorer and JsonTranscoding

[mcastagna-sa]

Hey guys, i'm having a problem with a project i'm working on and i wanted to see if i'm missing anything or maybe i've stumbled on a bug.

I have created a minimal project where i'm able to reproduce the behaviour, I'm goint to try to guide you pasting snippets of code here.

Program.cs

static void Main(string[] args)
 {
     var app = CreateHostBuilder(args).Build();

     app.UseRouting();

     app.MapControllers();

     app.MapGrpcService<GreeterService>();

     app.Run();
 }
  
 private static WebApplicationBuilder CreateHostBuilder(string[] args)
 {
     var builder = WebApplication.CreateBuilder(args);

     builder
         .WebHost.ConfigureKestrel((context, options) =>
         {
             options.ListenLocalhost(8080);
         });

     builder.Services.AddControllers();

     builder.Services.AddApiVersioning(options =>
          {
              options.ReportApiVersions = true;
          })
          .AddApiExplorer(options =>
          {
              options.GroupNameFormat = "'v'VVV";
              options.SubstituteApiVersionInUrl = true;                     
          });

     builder.Services
         .AddGrpc()
         .AddJsonTranscoding();

     return builder;
 }

V2Controller.cs

[ApiController]
[ApiVersion("2.0")]
[Produces("application/json")]
[Route("api/v{version:apiVersion}/controller/{param}")]
public class V2Controller : Controller
{
    [HttpGet]
    [Route("route")]
    public async Task<IActionResult> GetEndpoint()
    {
        return Ok("ok get v2");
    }
}

And greet.proto (This is the wiki example as you can see, just added the route i need to demostrate my point)

syntax = "proto3";

option csharp_namespace = "TestVersioningGRPC.Proto";
import "google/api/annotations.proto";

package greet;

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply) {
    option (google.api.http) = {        
      get: "/api/v1/controller/{name}/route"
    };
  }
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}

When i run this program, and try to hit the endpoint v2 with postman everything goes as expected.

But, instead, if i call v1, which should be responded by the jsontranscode, i get 404.

I've tracked this down to the call of AddApiExplorer. If i remove that call i'm able to get the v1 as i should.

What do you think about this? Is this the expected behaviour? Am i doing something wrong? Is this a bug? If it is, is a bug in the jsontranscoding or asp.versioning library?

Thank you so much for your time and sorry the lenght of this post. Let me know if you need anything else that could help you answering this.