RFR: 8340572: ConcurrentModificationException when sorting ArrayList sublists [v2]

[Attila Szegedi]

> Fixes a regression with #17818 where `ArrayList.subList(…).sort()` started incrementing `ArrayList.modCount` resulting in some cases throwing a `ConcurrentModificationException` where none was thrown before.
> 
> This change keeps the optimization from #17818 but restores the behavior where only sorting the `ArrayList` changes the mod count, but sorting its sublists does not.

Attila Szegedi has updated the pull request incrementally with one additional commit since the last revision:

  - Rename test to more descriptive
  - Add a test case for whole list sorting

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21250/files
  - new: https://git.openjdk.org/jdk/pull/21250/files/43185d7e..e0ae1cc9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21250&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21250&range=00-01

  Stats: 101 lines in 2 files changed: 59 ins; 42 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21250.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21250/head:pull/21250

PR: https://git.openjdk.org/jdk/pull/21250