Fire purge IslandEvents on the main thread

[tastybento]

Problem

Reported on Discord by a server admin running BentoBox 3.22.3 on Paper 26.2: /sgadmin purge confirm fails with

java.lang.IllegalStateException: IslandEvent may only be triggered synchronously.
        at io.papermc.paper.plugin.manager.PaperEventManager.callEvent(PaperEventManager.java:42)
        at world.bentobox.bentobox.api.events.island.IslandEvent$IslandEventBuilder.build(IslandEvent.java:410)
        at world.bentobox.bentobox.managers.PurgeRegionsService.delete(PurgeRegionsService.java:304)
        at world.bentobox.bentobox.api.commands.admin.purge.AbstractPurgeCommand.lambda$deleteEverything$0(AbstractPurgeCommand.java:89)
        at org.bukkit.craftbukkit.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:57)

Logs: https://mclo.gs/uGuzB8F, https://mclo.gs/rSn4KGX

PurgeRegionsService.delete() is dispatched from an async task by both AbstractPurgeCommand.deleteEverything() and HousekeepingManager, but it fired the DELETED / PURGED IslandEvents straight from that thread. Paper enforces that synchronous events are only fired on the main thread. Because the region files are deleted before the island loop, the crash left the region files gone but the island DB rows and cache entries intact, and the command reported the purge as failed.

Fix

delete() is now two phases:

1. Calling (async) thread – region file deletion, residual-region check, orphaned player-data cleanup. Islands that are fully reaped are collected.
2. Main thread – finalizeIslands() fires DELETED (if the island was never soft-deleted) and PURGED, and removes the island from the cache and database. This is scheduled with runTask and awaited via a CompletableFuture, so the boolean return and the "Purge complete" summary log still reflect the final state. When already on the main thread it runs inline.

The deleted sweep (days == 0) still defers DB rows to shutdown and never touches the scheduler.

Tests

• testDeleteOffMainThreadFinalizesViaScheduler – with isPrimaryThread() false, verifies finalization goes through the scheduler, the cache/DB are cleaned, and DELETED then PURGED fire in order.
• testDeleteOffMainThreadDeletedSweepDoesNotSchedule – deleted sweep off-thread never schedules or fires events.
• Existing PurgeRegionsServiceTest cases now stub isPrimaryThread() true to keep exercising the inline path.

Full suite: 3484 tests, 0 failures.

🤖 Generated with Claude Code

https://claude.ai/code/session_01XZRwXXfTUJLJFwSnzSgeRb

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
84.8% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud