Use `throw null` in refs (#15499)

Use `throw null` in refs instead of `return default(T)` or `return 0`.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/System.Net.Security/ref/System.Net.Security.cs b/src/System.Net.Security/ref/System.Net.Security.cs
index 1aa87f9067..eca6678174 100644
--- a/src/System.Net.Security/ref/System.Net.Security.cs
+++ b/src/System.Net.Security/ref/System.Net.Security.cs
@@ -155,7 +155,7 @@ namespace System.Net.Security
         public override int Read(byte[] buffer, int offset, int count) { throw null; }
         public override long Seek(long offset, System.IO.SeekOrigin origin) { throw null; }
         public override void SetLength(long value) { }
-        public virtual System.Threading.Tasks.Task ShutdownAsync() { return default(System.Threading.Tasks.Task); }
+        public virtual System.Threading.Tasks.Task ShutdownAsync() { throw null; }
         public void Write(byte[] buffer) { }
         public override void Write(byte[] buffer, int offset, int count) { }
     }