/// <summary>
 /// Initializes a new instance of the <see cref="ServerTimingMiddleware"/> class.
 /// </summary>
 /// <param name="next"></param>
 /// <param name="options"><see cref="ServerTimingMiddlewareOptions"/> to use to customize the current <see cref="ServerTimingMiddleware"/> behavior.</param>
 public ServerTimingMiddleware(RequestDelegate next, ServerTimingMiddlewareOptions options)
 {
     _next    = next ?? throw new ArgumentNullException(nameof(next));
     _options = options ?? new ServerTimingMiddlewareOptions();
 }
 public static void ConfigureServerTimingMiddleware(this IApplicationBuilder app, ServerTimingMiddlewareOptions options)
 {
     app.UseMiddleware <ServerTimingMiddleware>(options);
 }