RFR: Small cleanups in java.lang.ref

[Per Liden]

On 05/17/2018 10:03 PM, mark.reinhold at oracle.com wrote:
> 2018/5/16 18:31:15 -0700, martinrb at google.com:
>> I've been confused by NULL vs null for years.
> 
> That’s because `NULL` in ReferenceQueue.java refers to the singleton
> object `ReferenceQueue.NULL`, not the null value.  See the long comment
> at the top of Reference.java for an explanation.
> 
> To improve this you could change mentions of `NULL` in the comments to
> `ReferenceQueue.NULL`, but changing them to `null` would be incorrect.

The comments that were changed in the proposed patch refer to the 
Reference.next and Reference.discovered fields, not Reference.queue. So 
"null" should be correct there.

/Per

> 
>> 8203327: Small cleanups in java.lang.ref
>> http://cr.openjdk.java.net/~martin/webrevs/jdk/Reference-cleanup/
>> https://bugs.openjdk.java.net/browse/JDK-8203327
> 
> The other changes look fine.
> 
> - Mark
>