I need help converting an asp.net core webserver from C# to F# in linqpad 6

cheick

I am trying to translate this linqpad query to F#

void Main()
{
	using (var host = WebHost
						.CreateDefaultBuilder()
						.UseStartup<Startup>()
						.Build())
	{
		host.RunAsync();
		Util.ReadLine();
	}
}

[Route("api")]
public class TestController : ControllerBase
{
	[HttpGet("testGet")]
	public int TestGet()
	{
		return 121221;
	}

	[HttpPost("testPost")]
	public string TestPost()
	{
		return String.Empty;
	}
}

// Define other methods, classes and namespaces here
public class Startup
{
	public void ConfigureServices(IServiceCollection services)
	{
		services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
		services.AddRouteAnalyzer();
	}


	public void Configure(IApplicationBuilder app, IHostingEnvironment env, IApplicationLifetime applicationLifetime, IRouteAnalyzer routeAnalyzer)
	{
		app.UseMvc();
		applicationLifetime.ApplicationStarted.Register(() =>
			routeAnalyzer.GetAllRouteInformations().Select(i => i.ToString()).Dump("======== ALL ROUTE INFORMATION ========"));
	}
}

The query prints the following list of routes
RouteInformation{Area:"", HttpMethod: "GET", Path:"/api/testGet", Invocation:"TestController.TestGet (TestController.TestGet (LINQPadQuery))"}
RouteInformation{Area:"", HttpMethod: "POST", Path:"/api/testPost", Invocation:"TestController.TestPost (TestController.TestPost (LINQPadQuery))"}


Here is the F# version which does not show any routes

type Startup ()  = 
    member  this.ConfigureServices(services: IServiceCollection) =
        services
            .AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2) |> ignore
        services.AddRouteAnalyzer() |> ignore
        
    member this.Configure(app: IApplicationBuilder, env: IHostingEnvironment, applicationLifetime: IApplicationLifetime, routeAnalyzer:IRouteAnalyzer  ) = 
        app.UseMvc() |> ignore
        
        applicationLifetime.ApplicationStarted.Register(fun _ ->
                    (routeAnalyzer.GetAllRouteInformations()
                     |> Seq.map (sprintf "%O")).Dump("======== ALL ROUTE INFORMATION ========")
                    |> ignore
            ) |> ignore
            

[<Route("api")>]

type TestController() =
    inherit ControllerBase()

    [<HttpGet("testGet")>]
    member this.TestGet() =
        121221

    [<HttpPost("testPost")>]
    member this.TestPost() =
        String.Empty

let buildHost() =
		Microsoft.AspNetCore.WebHost
				.CreateDefaultBuilder()
                .UseStartup<Startup>()
                .Build()

let startServer() = 
    use host = buildHost()
    host.RunAsync() |> ignore
    Util.ReadLine()
    
startServer()

Any idea why i don't get the same result for both ?