RFR: 8246037: Shenandoah: update man pages to mention -XX:+UseShenandoahGC [v4]

[Y. Srinivas Ramakrishna]

On Thu, 28 Aug 2025 00:15:58 GMT, Rui Li <duke at openjdk.org> wrote:

>> Add documentation of Shenandoah to java man page
>> 
>> Aside from `-XX:+UseShenandoahGC`, I picked flags from [shenandoah_globals.hpp](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp) that are at product level but not experimental / diagnostic to avoid overwhelming info. Two additional flags match: `ShenandoahGCMode` and `ShenandoahGCHeuristics`
>
> Rui Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   gen shen and heuristics

Approved modulo a comment.

I also think we should to the extent possible make the listing of text common to man page and options list consistent. An example is the recent improvement you made in your most recent update to the man page for the heuristics option.  There may be other changes to the man page that came about as a result of this review. It would make sense to make those changes, where applicable, also to shenandoah_globals. This latter need not hold up this ticket but can be addressed separately in a follow up.

src/java.base/share/man/java.md line 2914:

> 2912: 
> 2913:     Possible heuristics are the following (when `-XX:ShenandoahGCMode` is
> 2914:     `generational`, the only supported option is the default, `adaptive`):

Move the parenthetic part to the previous paragraph and out of parentheses.

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Marked as reviewed by ysr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26907#pullrequestreview-3165915632
PR Review Comment: https://git.openjdk.org/jdk/pull/26907#discussion_r2308123862