Fix doc issue in resource extension. (#54193)

* Fix doc issue in resource extension.

* regen

Author: haiyuazhang

eng/packages/http-client-csharp-mgmt/generator/Azure.Generator.Management/src/Providers/ExtensionProvider.cs

@@ -173,7 +173,7 @@ private FormattableString BuildMockingDescription(CSharpType mockableType, Metho
             // In C# XML docs, method references look like: MethodName(TypeName1, TypeName2)
 
             // Build parameter type list as a simple string since XML doc cref attributes use simple type names
-            var parameterTypeNames = string.Join(", ", targetSignature.Parameters.Select(p => p.Type.Name));
+            var parameterTypeNames = string.Join(", ", targetSignature.Parameters.Select(p => p.Type.GetXmlDocTypeName()));
             var methodRef = $"{mockableType.Name}.{targetSignature.Name}({parameterTypeNames})";
 
             // Return a FormattableString that will be converted to: To mock this method, please mock <see cref="..."/> instead.

eng/packages/http-client-csharp-mgmt/generator/Azure.Generator.Management/src/Utilities/CSharpTypeExtensions.cs

@@ -36,5 +36,15 @@ public static bool IsModelType(this CSharpType type)
         {
             return ManagementClientGenerator.Instance.OutputLibrary.IsModelType(type);
         }
+
+        public static string GetXmlDocTypeName(this CSharpType type)
+        {
+            // For nullable value types, we need to append '?' to the type name for XML documentation
+            if (type.IsValueType && type.IsNullable)
+            {
+                return $"{type.Name}?";
+            }
+            return type.Name;
+        }
     }
 }

eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/baz.tsp

@@ -32,5 +32,10 @@ interface Bazs {
 
   list is ArmResourceListByParent<Baz>;
 
-  listBySubscription is ArmListBySubscription<Baz>;
+  listBySubscription is ArmListBySubscription<
+    Baz,
+    Parameters = {
+      @query("$top")
+      $top?: int32;
+    }>;
 }