After much debate on what to do when CompleteableFuture.whenComplete encounters an exception in both the source and the action, we chose what was acceptable to the most people - add the action's exception to the source exception as a suppressed exception. And added usage guidelines. And gave handle "top billing" over whenComplete.
http://cr.openjdk.java.net/~martin/webrevs/openjdk9/jsr166-jdk9-integration/ and the usual miscellaneous improvements.
