Code review request: JDK-8008670 (partial java.util.stream implementation)

[Brian Goetz]

At:
   http://cr.openjdk.java.net/~briangoetz/jdk-8008670/webrev/

there is a webrev of a subset of the implementation of java.util.stream, 
for review.  These are all new files.  None of these are public classes; 
they are internal interfaces for the Stream library, as well as some 
implementation classes.  This is about half the classes in the Streams 
package.

(The webrev includes changes to Map, but those are being reviewed 
separately, so just ignore those.)

We're asking people to focus their review on both the quality of API 
specification for these internal APIs, and the quality of implementation 
of the specified classes.  It may not be obvious how some of these work 
until you've seen the rest of it, but do what you can.