RFR: 8132984: incorrect type for Reference.discovered

[Kim Barrett]

> On Jan 18, 2021, at 12:28 PM, Peter Levart <plevart at openjdk.java.net> wrote:
> If you introduce a private method in Reference:
> 
>    private void enqueueFromPending() {
>        var q = queue;
>        if (q != ReferenceQueue.NULL) q.enqueue(this);
>    }
> 
> ...and use it Reference.processPendingReferences while loop like this:
> 
>            if (ref instanceof Cleaner) {
>                ...
>            } else {
>                ref.enqueueFromPending();
>            }
> 
> Then you can keep the signature of `ReferenceQueue.enqueue(Reference<? extends T> r)` and no unchecked casts are needed there.

Nice!  And this reverts all changes to ReferenceQueue.java

> But what you have is OK and much better than what was before.

Thanks, but I’m going to take your improvement.  I’ll update the PR once I’ve re-run some tests.