Nullable: System (most of it) (dotnet/coreclr#23774)

* Nullable: shared\System (most of it)

And some other things it touches.

* Nullable: src\System (most of it)

* Address PR feedback

Signed-off-by: dotnet-bot <dotnet-bot@microsoft.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/netcore/System.Private.CoreLib/shared/System/ResolveEventHandler.cs b/netcore/System.Private.CoreLib/shared/System/ResolveEventHandler.cs
index cb9af5de66c..829b146993a 100644
--- a/netcore/System.Private.CoreLib/shared/System/ResolveEventHandler.cs
+++ b/netcore/System.Private.CoreLib/shared/System/ResolveEventHandler.cs
@@ -2,9 +2,10 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Reflection;
 
 namespace System
 {
-    public delegate Assembly ResolveEventHandler(object sender, ResolveEventArgs args);
+    public delegate Assembly ResolveEventHandler(object? sender, ResolveEventArgs args);
 }