RFR: Fix NullPointerException on a parallel run [v5]

[Dmitry Bessonov]

On Thu, 1 Sep 2022 16:27:08 GMT, Jan Kratochvil <duke at openjdk.org> wrote:

> I have verified: https://github.com/jankratochvil/jtharness/tree/badnpe (=before this commit) does throw NPE https://github.com/jankratochvil/jtharness/tree/master does not throw NPE

Thank you! Looks we could add a tag for b24

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PR: https://git.openjdk.org/jtharness/pull/35