2026-April-29 - 2.7.15459

refactor(remove guava): Remove guava from java extras (#14285)

* Refactor(remove guava): remove guava in java-extras

* Remove ArgChecker from Java-Extras

* Remove more guava

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* fix: address review comments on validation and Guava removal

- Add null check for mnemonic in JMenuBuilder constructor
- Reject blank titles in JMenuBuilder.addMenuItem (consistent with constructor)
- Replace Preconditions.checkNotNull with Objects.requireNonNull in JMenuItemBuilder
- Improve error messages in Timers.fixedRateTimer (null vs blank distinction)
- Use Objects.requireNonNull in Retriable.withTask instead of bare IllegalArgumentException
- Remove redundant Files.exists check after Files.isDirectory in FileUtils.find

Agent-Logs-Url: https://github.com/triplea-game/triplea/sessions/92213287-80b0-4cb8-96a7-65015fa4e389

Co-authored-by: DanVanAtta <12397753+DanVanAtta@users.noreply.github.com>

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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: DanVanAtta <12397753+DanVanAtta@users.noreply.github.com>