RFR: JDK-8310913 Move ReferencedKeyMap to jdk.internal so it may be shared [v2]

[Jim Laskey]

On Thu, 29 Jun 2023 20:54:31 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> Jim Laskey has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Remove warning tied to String Templates
>
> src/java.base/share/classes/jdk/internal/util/ReferencedKeySet.java line 65:
> 
>> 63:  * replacing the value in the map entry instead of deleting the old entry and
>> 64:  * adding a new entry, otherwise replaced entries may end up with a strongly
>> 65:  * referenced key. {@link HashMap} and {@link ConcurrentHashMap} are known
> 
> Can this requirement be backed up with an assert checking for known ok HashMaps?
> It could catch mistakes (in debug builds).

It's known to be safe for HashMap and ConcurrentHashMap. Most others should fine but need some thought experiments to work it out.

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PR Review Comment: https://git.openjdk.org/jdk/pull/14684#discussion_r1247184193