[jdk8u-ri] RFR: 8201793: (ref) Reference object should not support cloning [v2]

[Iris Clark]

On Fri, 22 Apr 2022 17:20:33 GMT, Poonam Bajaj <poonam at openjdk.org> wrote:

>> This changeset backports the fix for 8201793 to jdk8u-ri.
>> 
>> With this change, `java.lang.ref.Reference::clone` method always throws `CloneNotSupportedException`.
>
> Poonam Bajaj has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fixed the javadoc comments

Updated @apiNote looks good.

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Marked as reviewed by iris (Author).

PR: https://git.openjdk.java.net/jdk8u-ri/pull/6