Remove TODOs related to AllowOutOfOrderMetadataProperty workarounds. (#977)

src/ModelContextProtocol.Core/Protocol/Reference.cs

@@ -39,6 +39,10 @@ public abstract class Reference
     /// <summary>
     /// Provides a <see cref="JsonConverter"/> for <see cref="Reference"/>.
     /// </summary>
+    /// <remarks>
+    /// Provides a polymorphic converter for the <see cref="Reference"/> class that doesn't  require
+    /// setting <see cref="JsonSerializerOptions.AllowOutOfOrderMetadataProperties"/> explicitly.
+    /// </remarks>
     [EditorBrowsable(EditorBrowsableState.Never)]
     public sealed class Converter : JsonConverter<Reference>
     {
@@ -95,8 +99,6 @@ public abstract class Reference
                 }
             }
 
-            // TODO: This converter exists due to the lack of downlevel support for AllowOutOfOrderMetadataProperties.
-
             switch (type)
             {
                 case "ref/prompt":