TreeGeneration

public class TreeGeneration {

    public static final List<ConfiguredFeature<?, ?>> OVERWORLD_TREES = new ArrayList<>();
    public static final List<ConfiguredFeature<?, ?>> END_TREES = new ArrayList<>();
    public static final List<ConfiguredFeature<?, ?>> NETHER_TREES = new ArrayList<>();

    private static <Config extends FeatureConfiguration> ConfiguredFeature<Config, ?> register(String name,
            ConfiguredFeature<Config, ?> configuredFeature) {
        return Registry.register(BuiltinRegistries.CONFIGURED_FEATURE, new ResourceLocation(TestMod.MODID, name),
                configuredFeature);
    }

    private static void registerTrees() {
        ConfiguredFeature<?, ?> tree = Feature.TREE
                .configured(new TreeConfiguration.TreeConfigurationBuilder(
                        new SimpleStateProvider(Blocks.PINK_CONCRETE.defaultBlockState()),
                        new FancyTrunkPlacer(5, 4, 6), new SimpleStateProvider(Blocks.PACKED_ICE.defaultBlockState()),
                        new SimpleStateProvider(Blocks.OAK_SAPLING.defaultBlockState()),
                        new RandomSpreadFoliagePlacer(ConstantInt.of(5), ConstantInt.of(5), ConstantInt.of(5), 7),
                        new TwoLayersFeatureSize(5, 1, 4)).ignoreVines().build())
                .decorated(Features.Decorators.HEIGHTMAP_WITH_TREE_THRESHOLD_SQUARED)
                .decorated(FeatureDecorator.COUNT_EXTRA
                        .configured(new FrequencyWithExtraChanceDecoratorConfiguration(10, .1f, 1)))
                .squared().count(20);
        OVERWORLD_TREES.add(register("funky_tree", tree));
    }

    @Mod.EventBusSubscriber(modid = TestMod.MODID, bus = Bus.FORGE)
    public static class ForgeBusSubscriber {
        @SubscribeEvent
        public static void biomeLoading(BiomeLoadingEvent event) {
            final List<Supplier<ConfiguredFeature<?, ?>>> features = event.getGeneration()
                    .getFeatures(Decoration.VEGETAL_DECORATION);
            switch(event.getCategory()) {
                case NETHER -> TreeGeneration.OVERWORLD_TREES.forEach(tree -> features.add(() -> tree));
                case THEEND -> TreeGeneration.END_TREES.forEach(tree -> features.add(() -> tree));
                default -> TreeGeneration.NETHER_TREES.forEach(tree -> features.add(() -> tree));
            }
        }
    }

    @Mod.EventBusSubscriber(modid = TestMod.MODID, bus = Bus.MOD)
    public static class ModBusSubscriber {
        @SubscribeEvent
        public static void commonSetup(FMLCommonSetupEvent event) {
            event.enqueueWork(TreeGeneration::registerTrees);
        }
    }
}