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

[Mandy Chung]

On Wed, 20 Apr 2022 00:59:26 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`.

jdk/src/share/classes/java/lang/ref/Reference.java line 255:

> 253:      * @throws  CloneNotSupportedException always
> 254:      *
> 255:      * @since 8

This method is only present in JDK 8u42 (RI) and 8u352 and later releases.  It's not in existing 8u releases >= 8u45 and < 8u352.   Neither 8 or 8u42 would cause confusion.  A suggestion is to use `@apiNote` to indicate which MR this method is defined:


@apiNote This method is defined in Java SE 8 Maintenance Release 4.

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