Revert Copilot autofix and make DeserializeFromXml non-generic

Reverts c29ce27 (Copilot autofix broke the build with CS0030) and
applies the proper fix: drop the false generality entirely. The method
only ever deserialises OoklaServerList, so the generic parameter, the
typeof(T) runtime check, and the (T)(object) cast were all unnecessary
ceremony. Returning OoklaServerList? directly eliminates the CodeQL
'useless upcast' finding cleanly.

Co-authored-by: Frank Ray <FrankRay78@users.noreply.github.com>

Author: github-actions[bot]

src/NetPace.Core.Tests/Clients/Ookla/Extensions/XmlExtensionsTests.cs

@@ -26,7 +26,7 @@ public void Deserialize_RepresentativeOoklaResponse_PopulatesAllRequiredAttribut
             </settings>
             """;
 
-        var result = Xml.DeserializeFromXml<OoklaServerList>();
+        var result = Xml.DeserializeFromXml();
 
         result.ShouldNotBeNull();
         result.Servers.ShouldNotBeNull();
@@ -55,7 +55,7 @@ public void Deserialize_OptionalAttributesPresent_PopulatesCountryAndHost()
             </settings>
             """;
 
-        var result = Xml.DeserializeFromXml<OoklaServerList>();
+        var result = Xml.DeserializeFromXml();
 
         var server = result!.Servers!.Single();
         server.Country.ShouldBe("United Kingdom");
@@ -76,7 +76,7 @@ public void Deserialize_OptionalAttributesAbsent_LeavesCountryAndHostNull()
             </settings>
             """;
 
-        var result = Xml.DeserializeFromXml<OoklaServerList>();
+        var result = Xml.DeserializeFromXml();
 
         var server = result!.Servers!.Single();
         server.Country.ShouldBeNull();
@@ -102,7 +102,7 @@ public void Deserialize_NumericAttributes_UsesInvariantCultureUnderCommaDecimalL
         {
             CultureInfo.CurrentCulture = new CultureInfo("de-DE");
 
-            var result = Xml.DeserializeFromXml<OoklaServerList>();
+            var result = Xml.DeserializeFromXml();
 
             var server = result!.Servers!.Single();
             server.Latitude.ShouldBe(51.5074);
@@ -126,7 +126,7 @@ public void Deserialize_EmptyServersElement_ReturnsEmptyOrNullCollection()
             </settings>
             """;
 
-        var result = Xml.DeserializeFromXml<OoklaServerList>();
+        var result = Xml.DeserializeFromXml();
 
         result.ShouldNotBeNull();
         (result.Servers is null || result.Servers.Length == 0).ShouldBeTrue();
@@ -139,7 +139,7 @@ public void Deserialize_MalformedXml_ThrowsXmlException()
 
         const string Xml = "<settings><servers><server id=\"1\" /></servers"; // unclosed
 
-        var thrown = Should.Throw<Exception>(() => Xml.DeserializeFromXml<OoklaServerList>());
+        var thrown = Should.Throw<Exception>(() => Xml.DeserializeFromXml());
 
         // Accept either an XmlException directly or an InvalidOperationException wrapping one
         var isXmlOrWrapped = thrown is XmlException

src/NetPace.Core/Clients/Ookla/Extensions/XmlExtensions.cs

@@ -6,14 +6,8 @@ namespace NetPace.Core.Clients.Ookla.Extensions;
 
 internal static class XmlExtensions
 {
-    internal static T? DeserializeFromXml<T>(this string data)
+    internal static OoklaServerList? DeserializeFromXml(this string data)
     {
-        if (typeof(T) != typeof(OoklaServerList))
-        {
-            throw new NotSupportedException(
-                $"DeserializeFromXml only supports {nameof(OoklaServerList)}; requested {typeof(T).FullName}.");
-        }
-
         var doc = XDocument.Parse(data);
         var settings = doc.Element("settings")
             ?? throw new XmlException("Expected <settings> root element.");
@@ -23,14 +17,14 @@ internal static class XmlExtensions
 
         if (serversElement is null)
         {
-            return (T)serverList;
+            return serverList;
         }
 
         var serverElements = serversElement.Elements("server").ToArray();
         if (serverElements.Length == 0)
         {
             serverList.Servers = Array.Empty<OoklaServer>();
-            return (T)serverList;
+            return serverList;
         }
 
         var servers = new OoklaServer[serverElements.Length];
@@ -40,7 +34,7 @@ internal static class XmlExtensions
         }
 
         serverList.Servers = servers;
-        return (T)serverList;
+        return serverList;
     }
 
     private static OoklaServer ParseServer(XElement element)

src/NetPace.Core/Clients/Ookla/OoklaSpeedtest.cs

@@ -35,7 +35,7 @@ public OoklaSpeedtest(OoklaSpeedtestSettings? speedtestSettings = null, HttpClie
     public async Task<IServer[]> GetServersAsync(CancellationToken cancellationToken = default)
     {
         var serversXml = await httpClient.GetStringAsync(settings.ServerDiscovery.ServersUrl, cancellationToken).ConfigureAwait(false);
-        var servers = serversXml.DeserializeFromXml<OoklaServerList>()?.Servers ?? Array.Empty<OoklaServer>();
+        var servers = serversXml.DeserializeFromXml()?.Servers ?? Array.Empty<OoklaServer>();
         return servers.Where(s =>
                 !string.IsNullOrWhiteSpace(s.Location) &&
                 !string.IsNullOrWhiteSpace(s.Sponsor) &&