STS allows to bypass any checked exceptions

[Attila Kelemen]

> If we are already on the subject, as you stated, STS#handleComplete has only 2 possible states, success and failure, so why not completely separate them:
>
> STS#handleSuccess(T result, Callable task [, boolean cancelled])
> STS#handleFailure(Throwable exception, Callable task [, boolean cancelled]) (note that we can’t use parameterize exception here)
>

I don't think there would be even an easy way around this, because you
can't reasonably create a common base type for the two results
(previously - as Rémi said - I thought sealed interfaces would be
solution, but that is impossible due to the generic parameter), unless
you pass the `TaskHandle` where you could call the appropriate method
based on the state.

Also, I'm not even sure why the `Callable` is being passed around
here. What is STS supposed to do with that? It can't really use it as
an ID, because you might be running the same `Callable` instance
multiple times. Also, passing it just makes you nervous wrapping it
(which you might be forced to do in some cases). If a feature of being
able to distinguish between tasks is needed, then `fork` should allow
associating an additional custom object with the submitted `Callable`.
But - to me - it seems that is going too far with STS.