[concurrency-interest] We need to add blocking methods to CompletionStage!

[Martin Buchholz]

On Sun, Sep 25, 2016 at 2:22 PM, David Holmes <davidcholmes at aapt.net.au>
wrote:

>
> Yet we somehow added the clarification with no regard as to whether cancel
> returned true or not. That seems wrong.
>

Yikes!  I had always assumed that cancel was not permitted to leave the
Future incomplete, perhaps influenced by the wording,

"""After this method returns, subsequent calls to {@link #isDone} will
always return {@code true}."""

It's much more in the spirit of Java to throw an exception if the future
cannot be completed.  It's never come up, I think.