Nancy asp.net hosting katana startup test

INancyOwinStartup.cs

namespace AutoStartupTest
{
    using Owin;

    public interface INancyOwinStartup
    {
        void Configuration(IAppBuilder builder);
    }
}

NancyAutoStartup.cs

namespace AutoStartupTest
{
    using System;
    using System.Linq;

    using Nancy.Bootstrapper;

    using Owin;

    public class NancyAutoStartup
    {
         public void Configuration(IAppBuilder builder)
         {
             var userConfigs = GetUserConfigs();

             if (userConfigs.Length > 1)
             {
                 throw new InvalidOperationException(string.Format("Discovered {0} implementations of INancyOwinStartup ({1}), unable to continue.", userConfigs.Length, userConfigs.Select(t => t.FullName).Aggregate((n1, n2) => n1 + ", " + n2)));
             }

             if (userConfigs.Length == 0)
             {
                 this.BuildDefaultConfig(builder);
             }
             else
             {
                 this.BuildUserConfig(builder, userConfigs[0]);
             }
         }

        private static Type[] GetUserConfigs()
        {
            return AppDomainAssemblyTypeScanner.TypesOf<INancyOwinStartup>().ToArray();
        }

        private void BuildDefaultConfig(IAppBuilder builder)
        {
            builder.UseNancy();
        }

        private void BuildUserConfig(IAppBuilder builder, Type userConfigType)
        {
            var userConfig = ((INancyOwinStartup)Activator.CreateInstance(userConfigType));

            userConfig.Configuration(builder);
        }
    }
}