hg: jdk8/tl/jdk: 8001642: Add Optional<T>, OptionalDouble, OptionalInt, OptionalLong

[Brian Goetz]

> Has the optional classes been verified to serialize/deserialize correctly?
> 
They are not serializable.  
> Finally, are these utilities critical to some other part JDK 8 that they were pushed out now as opposed to JDK 9?
> 
> 
They are part of the libraries being added by JSR-335 / Project Lambda.  There is extensive discussion on Optional on lambda-dev and the JSR 335 EG lists.