RFR: 8288: Clean up warnings

[Alex Macdonald]

On Mon, 4 Nov 2024 15:27:19 GMT, Marcus Hirt <hirt at openjdk.org> wrote:

> Cleaning up some of the warnings in core in preparation for hack-commit-push (https://switzerland2024.hack-commit-pu.sh/). The ones related to the security manager being deprecated will be taken care of in JMC 10 (https://bugs.openjdk.org/browse/JMC-8289).

Marked as reviewed by aptmac (Reviewer).

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PR Review: https://git.openjdk.org/jmc/pull/604#pullrequestreview-2413429538