Major Description
It seems that it is possible that a Task is submitted to be executed on the IOThread via doOnIOThread but is never being executed because the Connection is already closed. This might result in a Thread hanging indefinetely if it calls ACO.doSync() on the ListeningFuture of the Task.
This was occurring in the cleanup code to TransactionalTransferTest#receiveTransactionalAcquisitionFlowFailsDueToUnknownTransactionId.