Fix ThrowIfNull

SystemExtensions.NetCore/Extensions/ObjectExtensions.cs

@@ -1,10 +1,11 @@
-using System.Runtime.CompilerServices;
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.CompilerServices;
 
 namespace System.Core.Extensions;
 
 public static class ObjectExtensions
 {
-    public static T ThrowIfNull<T>([ValidatedNotNull] this T obj, [CallerArgumentExpression("obj")] string? paramName = null)
+    public static T ThrowIfNull<T>([NotNull] this T obj, [CallerArgumentExpression("obj")] string? paramName = null)
         where T : class
     {
         if (obj is null)
@@ -14,9 +15,4 @@ public static class ObjectExtensions
 
         return obj;
     }
-
-    [AttributeUsage(AttributeTargets.Parameter)]
-    sealed class ValidatedNotNullAttribute : Attribute
-    {
-    }
 }