RFR: 8274560: JFR: Add test for OldObjectSample event when using Shenandoah

[Aleksey Shipilev]

On Thu, 30 Sep 2021 10:57:13 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Similar to JDK-8248302, we would like to have a test for Shenandoah. Current `jdk/jfr/event/oldobject/TestObjectDescription.java` fails with Shenandoah and should be excluded. 
> 
> Additional testing:
>  - [x] `jdk/jfr/event/oldobject/TestObjectDescription.java`, default: still passes
>  - [x] `jdk/jfr/event/oldobject/TestObjectDescription.java`, `-XX:+UseShenandoahGC`: now skipped
>  - [x] `jdk/jfr/event/oldobject/TestObjectDescription.java`, `-XX:+UseZGC`: still skipped
>  - [x] `jdk/jfr/event/oldobject/TestShenandoah.java`, out of box: passes
>  - [x] `jdk/jfr/event/oldobject/TestShenandoah.java`, `-XX:+UseShenandoahGC`: passes
>  - [x] `jdk/jfr/event/oldobject/TestShenandoah.java`, `-XX:+UseZGC`: skipped

Any takers? :)

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PR: https://git.openjdk.java.net/jdk/pull/5773