Is it safe to use the ContinueWith(...) method on a TaskCompletionSource.Task if the TaskCompletionSource.SetResult(...) has already been
ContinueWith(...)
TaskCompletionSource.Task
TaskCompletionSource.SetResult(...)
If the specified task has already completed by the time ContinueWith is called, the synchronous continuation will run on the thread calling ContinueWith. https://msdn.microsoft.com/en-us/library/dd321576(v=vs.110).aspx