docs: @Override
    public synchronized boolean cancel(boolean mayInterruptIfRunning) {
      if (isDone())
        return false;
  
      boolean cancelResult = super.cancel(mayInterruptIfRunning);
      if (delegate != null)
        cancelResult = delegate.cancel(mayInterruptIfRunning);
      Throwable failure = new CancellationException();
      complete(null, failure);
      executor.handleComplete(ExecutionResult.failure(failure), execution);
      return cancelResult;
    }