4.Post.POCO.Startup.cs

public class Startup
{
	public IConfiguration Configuration { get; }

	// ... código omitido
	
	public void ConfigureServices(IServiceCollection services)
	{
		services.AddSingleton(Configuration);
		services.Configure<MySettings>(Configuration.GetSection("MySettings"));
	}

	public void Configure(IApplicationBuilder app, IHostingEnvironment env)
	{
		// ... código omitido
	}
}