RFR: 8378806: Genshen: Add scope of collection to end of cycle message in JMX notification [v2]

[William Kemper]

> Right now, the action field in ShenandoahCycles bean's GC notification is just "end of GC cycle". It would be better if the generational mode's event indicated whether it was a young, old or global cycle.

William Kemper has updated the pull request incrementally with one additional commit since the last revision:

  Organize imports

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Changes:
  - all: https://git.openjdk.org/jdk/pull/29950/files
  - new: https://git.openjdk.org/jdk/pull/29950/files/83baee8d..e206dd77

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29950&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29950&range=00-01

  Stats: 7 lines in 1 file changed: 3 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/29950.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29950/head:pull/29950

PR: https://git.openjdk.org/jdk/pull/29950