public class ExampleMod implements ModInitializer {
  private static ConfiguredFeature<?, ?> OVERWORLD_WOOL_ORE_CONFIGURED_FEATURE = new ConfiguredFeature
      (Feature.ORE, new OreFeatureConfig(
          OreConfiguredFeatures.STONE_ORE_REPLACEABLES,
          Blocks.WHITE_WOOL.getDefaultState(),
          9)); // vein size

  public static PlacedFeature OVERWORLD_WOOL_ORE_PLACED_FEATURE = new PlacedFeature(
      RegistryEntry.of(OVERWORLD_WOOL_ORE_CONFIGURED_FEATURE),
      Arrays.asList(
          CountPlacementModifier.of(20), // number of veins per chunk
          SquarePlacementModifier.of(), // spreading horizontally
          HeightRangePlacementModifier.uniform(YOffset.getBottom(), YOffset.fixed(64))
      )); // height

  @Override
  public void onInitialize() {
    Registry.register(BuiltinRegistries.CONFIGURED_FEATURE,
        new Identifier("tutorial", "overworld_wool_ore"), OVERWORLD_WOOL_ORE_CONFIGURED_FEATURE);
    Registry.register(BuiltinRegistries.PLACED_FEATURE, new Identifier("tutorial", "overworld_wool_ore"),
        OVERWORLD_WOOL_ORE_PLACED_FEATURE);
    BiomeModifications.addFeature(BiomeSelectors.foundInOverworld(), GenerationStep.Feature.UNDERGROUND_ORES,
        RegistryKey.of(Registry.PLACED_FEATURE_KEY,
            new Identifier("tutorial", "overworld_wool_ore")));
  }
}