Bonemealing saplings results in tree different than the sapling due to using shared static variable for all events #13092
Description
Expected behavior
Saplings (and the resulting StructureGrowEvent TreeType) should result in the corresponding tree growing.
Observed/Actual behavior
Different plants and structures grow instead.
Steps/models to reproduce
We haven't been able to reproduce this in a small scale (development servers), only on our production server with ~40 online players spread on a large map and multiple worlds. We have a custom tree growing plugin (developed by us) that relies on the StructureGrowEvent and uses the .getSpecies() (TreeType) directly, so that value is already wrong:
This is likely due to this singleton/static value logic used in multiple places (eg. SaplingBlock.java):
org.bukkit.TreeType treeType = SaplingBlock.treeType;
SaplingBlock.treeType = null;
And this value is shared for all grow events. If an another plant grows before the bone mealing is complete, it will get replaced and grown instead.
Similar code is also used in ItemStack.java (in useOn method), I'm not sure which gets used but both rely on the same logic (depending on TreeGrower.java to set the value).
Plugin and Datapack List
Custom plugins: Abydos, AbydosPluginCheck
Apollo-Bukkit, BlueMap, CoreProtect, FastAsyncWorldEdit, GSit, InvSeePlusPlus, LuckPerms, Multiverse-Core, packetevents, ProtocollLib, SimpleWarps, SuperVanish, WorldGuard
Paper version
This server is running Paper version 1.21.8-60-main@29c8822 (2025-09-06T21:49:13Z) (Implementing API version 1.21.8-R0.1-SNAPSHOT)
Other
No response