public RedirectFilterMiddleware(RedirectPolicyOptions options)
 {
     AllowedBaseUris = options.AllowedBaseUris ?? throw new ArgumentNullException(nameof(options));
 }
 public static IServiceCollection AddRedirectPolicy(this IServiceCollection services, RedirectPolicyOptions options)
 {
     services.AddSingleton <RedirectFilterMiddleware>();
     services.AddSingleton(options);
     return(services);
 }