Startup PostConfigure Method implementation

5.Post.SettingsValidation.PostConfigureMethod.Startup.cs

public class Startup
{
	// ... código omitido
	
	public void ConfigureServices(IServiceCollection services)
	{
		services.AddSingleton(Configuration);

		services.Configure<MySettings>(Configuration.GetSection("MySettings"));
		
		services.PostConfigure<MySettings>(options =>
		{
			if (!options.Validate())
			{
				throw new InvalidOperationException($"Invalid {nameof(MySettings)} options. {string.Join(",", options.ValidationResult)}");
			}
		});
	}
}