System.Threading.Tasks.Sources

 namespace System.Threading.Tasks.Sources {
+    public struct ManualResetValueTaskSourceCore<TResult> {
+        public bool RunContinuationsAsynchronously { get; set; }
+        public short Version { get; }
+        public TResult GetResult(short token);
+        public ValueTaskSourceStatus GetStatus(short token);
+        public void OnCompleted(Action<object> continuation, object state, short token, ValueTaskSourceOnCompletedFlags flags);
+        public void Reset();
+        public void SetException(Exception error);
+        public void SetResult(TResult result);
+    }
 }