use System.Net.IPNetwork for ForwardedHeadersOptions

Author: WeihanLi

src/Middleware/HttpOverrides/src/ForwardedHeadersOptions.cs

@@ -3,6 +3,7 @@
 
 using Microsoft.AspNetCore.HttpOverrides;
 using IPAddress = System.Net.IPAddress;
+using IPNetwork = System.Net.IPNetwork;
 
 namespace Microsoft.AspNetCore.Builder;
 

src/Middleware/HttpOverrides/test/ForwardedHeadersMiddlewareTest.cs

@@ -1092,7 +1092,7 @@ public async Task XForwardForIPv4ToIPv6Mapping(string forHeader, string knownPro
             var knownNetworkParts = knownNetwork.Split('/');
             var networkIp = IPAddress.Parse(knownNetworkParts[0]);
             var prefixLength = int.Parse(knownNetworkParts[1], CultureInfo.InvariantCulture);
-            options.KnownNetworks.Add(new IPNetwork(networkIp, prefixLength));
+            options.KnownNetworks.Add(new System.Net.IPNetwork(networkIp, prefixLength));
         }
 
         using var host = new HostBuilder()