C# Kestrel pipeline branch

UseBranchForPort.cs

using System;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Hosting.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;

namespace Swerve
{
    public static class ApplicationBuilderExtensions
    {
        public static IApplicationBuilder UseBranchForPort(this IApplicationBuilder app, int port,
            Action<IServiceCollection> servicesConfiguration, Action<IApplicationBuilder> appBuilderConfiguration)
        {
            var webHost = new WebHostBuilder()
                .UseKestrel()
                .ConfigureServices(servicesConfiguration)
                .UseStartup<EmptyStartup>()
                .Build();
            var serviceProvider = webHost.Services;
            var serverFeatures = webHost.ServerFeatures;

            var appBuilderFactory = serviceProvider.GetRequiredService<IApplicationBuilderFactory>();
            var branchBuilder = appBuilderFactory.CreateBuilder(serverFeatures);
            var factory = serviceProvider.GetRequiredService<IServiceScopeFactory>();

            branchBuilder.Use(async (context, next) =>
            {
                using (var scope = factory.CreateScope())
                {
                    context.RequestServices = scope.ServiceProvider;
                    await next();
                }
            });

            appBuilderConfiguration(branchBuilder);

            var branchDelegate = branchBuilder.Build();

            return app.MapWhen(x => x.Request.Host.Port == port, builder =>
            {
                builder.Use(async (context, next) =>
                {
                    await branchDelegate(context);
                });
            });
        }

        private class EmptyStartup
        {
            public void ConfigureServices(IServiceCollection services) { }

            public void Configure(IApplicationBuilder app) { }
        }
    }
}