Fix nullable annotation

Commit migrated from https://github.com/dotnet/coreclr/commit/420884ff6f4244f0e6ca8c5cfc2f59a708d89379

diff --git a/src/libraries/System.Private.CoreLib/src/System/Threading/WaitHandle.cs b/src/libraries/System.Private.CoreLib/src/System/Threading/WaitHandle.cs
index dae3ddc..582aca4 100644 (file)
--- a/src/libraries/System.Private.CoreLib/src/System/Threading/WaitHandle.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Threading/WaitHandle.cs
@@ -190,7 +190,7 @@ namespace System.Threading
                     Math.Min(MaxWaitHandles, 2 * currentLength))];
             }
 
-            return safeWaitHandles;
+            return safeWaitHandles!;
         }
 
         private static void ReturnSafeWaitHandleArray(SafeWaitHandle?[]? safeWaitHandles)