RFR: 8350147: Replace example in KEM class with the one from JEP 452 [v3]

[Weijun Wang]

On Sat, 15 Feb 2025 22:33:46 GMT, Bradford Wetmore <wetmore at openjdk.org> wrote:

>> The example code in the JEP was much clearer than that in the current `KEM` class.  It's easier to keep the various nested classes straight, rather than using `var`s which require scrolling to see what the return types are. 
>> 
>> Added/tweaked example for clarity.
>> 
>> Generated/checked javadocs, but no regression/JCK tests is necessary.
>
> Bradford Wetmore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Further codereview Comments from Weijun

LGTM. Thanks!

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Marked as reviewed by weijun (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/23652#pullrequestreview-2619504934