using Microsoft.Extensions.DependencyInjection;

using System;

using System.Collections.Generic;

using System.Threading.Tasks;

​

public class Program

{

    public delegate Task OnBeforeResponseAsync(string value);

    public static async Task Main()

    {

        var serviceProvider = new ServiceCollection()

            .BuildServiceProvider();

​

        var handlers = serviceProvider.GetServices<OnBeforeResponseAsync>();

        foreach (var handleAsync in handlers)

        {

            await handleAsync("test");

        }

        Console.WriteLine();

    }

}