Add comment

Author: sebastienros

src/Hosting/Hosting/src/Internal/HostingMetrics.cs

@@ -69,7 +69,8 @@ public void RequestEnd(string protocol, string scheme, string method, string? ro
             tags.Add("http.response.status_code", GetBoxedStatusCode(statusCode));
             if (route != null)
             {
-                var httpRoute = (route == string.Empty) ? "/" : route;
+                // An empty route ("") is valid and equivalent to "/" hence it's normalized for metrics
+                var httpRoute = route == string.Empty ? "/" : route;
                 tags.Add("http.route", httpRoute);
             }