Retarder- reorganizing the project to easy use- part 2

Now it is the moment to start reorganizing the project to be easy to use by other programmers. I want,instead of registering the services manually,to can use .AddRetarder and .UseRetarder. So I create a new project,NetCoreRetarderCore.csproj,and move there the RetarderMiddleware . The only new thing is the extension class RetarderExtensions

using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using System;
using System.Collections.Generic;
using System.Text;

namespace NetCoreRetarderCore
{
    public static class RetarderExtensions
    {
        public static void AddRetarder(this IServiceCollection serviceCollection)
        {
            serviceCollection.AddTransient<RetarderMiddleware>();
        }
        public static void UseRetarder(this IApplicationBuilder app)
        {
            app.UseMiddleware<RetarderMiddleware>();
        }

    }
}

This let’s me reorganize the Startup as

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using NetCoreRetarderCore;

namespace NetCoreRetarder
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
            services.AddRetarder();
        }
        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app,IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

            app.UseAuthorization();
            app.UseRetarder();
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

You can find code at https://github.com/ignatandrei/NetCoreRetarder/commits/version2_reorg