RFR: 6543126: Level.known can leak memory

[Mandy Chung]

> On Jul 29, 2016, at 4:54 AM, Daniel Fuchs <daniel.fuchs at oracle.com> wrote:
> 
> http://cr.openjdk.java.net/~dfuchs/webrev_6543126/webrev.01/

This looks pretty good.

Since KnownLevel is now a Reference, I suggest to change KnownLevel::findByName, findByValue and findByLocalizedLevelName to return Optional<Level> instead such that the parse method implementaiton could be simplified.

Mandy