RFR: 8246037: Shenandoah: update man pages to mention -XX:+UseShenandoahGC [v3]

[Y. Srinivas Ramakrishna]

On Tue, 26 Aug 2025 22:53:07 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:
> 
>   Update for comments

One small comment/suggestion. Rest looks good to me.

Approving modulo that suggestion.

src/java.base/share/man/java.md line 2915:

> 2913:     `adaptive`
> 2914:     :   To maintain the given amount of free heap at all times, even during
> 2915:         the GC cycle.

May be this part (and in `shenandoah_globals.hpp`) could be changed so as not to repeat the description of `adaptive`, by stating that the default setting is adaptive, but replacing the current description of `adaptive` at line 2914 with the text earlier at line 2909-2911.

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Marked as reviewed by ysr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26907#pullrequestreview-3162122472
PR Review Comment: https://git.openjdk.org/jdk/pull/26907#discussion_r2305543383