# System.ComponentModel.Design

``` diff
 namespace System.ComponentModel.Design {
     public class CheckoutException : ExternalException {
-        protected CheckoutException(SerializationInfo info, StreamingContext context);
+        [EditorBrowsableAttribute(EditorBrowsableState.Never)]
+        [ObsoleteAttribute("This API supports obsolete formatter-based serialization. It should not be called or extended by application code.", DiagnosticId="SYSLIB0051", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
+        protected CheckoutException(SerializationInfo info, StreamingContext context);
     }
     public interface ISelectionService {
-        object PrimarySelection { get; }
+        object? PrimarySelection { get; }
     }
 }
```

