RFR: 8330577: G1 sometimes sends jdk.G1HeapRegionTypeChange for non-changes [v2]

[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 with a new target base due to a merge or a rebase. The pull request now contains three commits:

 - Merge branch 'master' into submit/80330577-jfr-heap-region-type-transitions
 - Fix errorneous Old->Old transitions which actually were Free->Old.
   
   Add test
 - JDK-8330577

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Changes: https://git.openjdk.org/jdk/pull/19389/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19389&range=01
  Stats: 113 lines in 2 files changed: 110 ins; 0 del; 3 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