code: private final void cancelCancellable() {
          if (timeoutMessageCancellable != null
                  && !timeoutMessageCancellable.isCancelled()) {
              timeoutMessageCancellable.cancel();
          }
          if (pollMessageCancellable != null
                  && !pollMessageCancellable.isCancelled()) {
              pollMessageCancellable.cancel();
          }
      }
docs: Cancel cancellable.