RFR: 8256167: Convert JDK use of `Reference::get` to `Reference::refersTo`

[Aleksey Shipilev]

On Thu, 3 Dec 2020 22:54:54 GMT, Mandy Chung <mchung at openjdk.org> wrote:

> This patch replaces some uses of `Reference::get` to `Reference::refersTo` to avoid keeping a referent strongly reachable that could cause unnecessary delay in collecting such object.   I only made change in some but not all classes in core libraries when working with Kim on `Reference::refersTo`.    The remaining uses are left for the component owners to convert at appropriate time.

Replacements look fine to me.

src/java.base/share/classes/java/util/WeakHashMap.java line 291:

> 289:         if (e.refersTo(key)) return true;
> 290: 
> 291:         // then checks for equality

Obnoxiously minor nit: plurality is inconsistent. `check if the given entry...` above, and `then check[s] for equality`. Should be `...then check for equality`?

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Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1609