RFR : JDK-8001642 : Add Optional<T>, OptionalDouble, OptionalInt, OptionalLong

[Brian Goetz]

> For Option lovers, one way to view this: it enables someone to provide their own Option instead of the one we provide. Right? If not, then I'm less favorable.
> 

No, not right.  It prevents people from distinguishing between a stream that is empty and a stream containing only the "orElse" value.  Just like Map.get() prevents distinguishing between "not there" and "mapped to null."