結論

Java Code

java

    public BiomeBase getBiomeBase(Location location) {
        World bukkitWorld = location.getWorld();
        if(bukkitWorld == null)
            return null;

        int x = location.getBlockX();
        int y = location.getBlockY();
        int z = location.getBlockZ();
        net.minecraft.world.level.World nmsWorld = ((CraftWorld) bukkitWorld).getHandle();
        return nmsWorld.getNoiseBiome(x >> 2, y >> 2, z >> 2).a();
    }
    public MinecraftKey getBiomeKey(Location location) {
        DedicatedServer dedicatedServer = ((CraftServer) Bukkit.getServer()).getServer();
        IRegistry<BiomeBase> registry = dedicatedServer.aZ().d(Registries.at);

        return registry.b(getBiomeBase(location));
    }

Kotlin Code

Kotlin

    private fun getBiomeBase(loc: Location): BiomeBase {
        val bukkitWorld = loc.world
        val x = loc.blockX
        val y = loc.blockY
        val z = loc.blockZ
        val nmsWorld: net.minecraft.world.level.World = (bukkitWorld as CraftWorld).handle
        return nmsWorld.getNoiseBiome(x shr 2, y shr 2, z shr 2).a()
    }

    fun getBiomeKey(loc: Location): MinecraftKey? {
        val dedicatedServer = (Bukkit.getServer() as CraftServer).server
        val registry: IRegistry<BiomeBase?> = dedicatedServer.aZ().d(Registries.at)
        return registry.b(getBiomeBase(loc))
    }

未来のためのメモ

dedicatedServer.aZ(): MinecraftServer.registryAccess()
dedicatedServer.aZ().d(): RegistryAccess.ownedRegistryOrThrow()
Registries.at: Registries.BIOME

参考