RFR: 8330577: G1 sometimes sends jdk.G1HeapRegionTypeChange for non-changes [v3]

[Thomas Schatzl]

> Hi all,
> 
>   please review this change that avoids posting Free->Free and Old->Old region transitions in JFR.
> 
> The reason for these could have been:
>   * Free->Free: heap shrinking and full gc
>   * Old->Old: heap shrinking, full gc or evacuation failure in an old region
> 
> Parts of this change has been contributed by @ansteiner , crediting him for this (the first commit).
> 
> Testing: tier1-3, tier5, all "detailed" JFR test cases
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  Fix compilation after merge

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/19389/files
  - new: https://git.openjdk.org/jdk/pull/19389/files/be8585b3..75c8027c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19389&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19389&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/19389.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19389/head:pull/19389

PR: https://git.openjdk.org/jdk/pull/19389