add some generated typed/tag keys

paper-api-generator/generated/io/papermc/paper/registry/keys/tags/EnchantmentTagKeys.java

@@ -0,0 +1,323 @@
+package io.papermc.paper.registry.keys.tags;
+
+import static net.kyori.adventure.key.Key.key;
+
+import io.papermc.paper.generated.GeneratedFrom;
+import io.papermc.paper.registry.RegistryKey;
+import io.papermc.paper.registry.tag.TagKey;
+import net.kyori.adventure.key.Key;
+import org.bukkit.MinecraftExperimental;
+import org.bukkit.enchantments.Enchantment;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Vanilla keys for {@link RegistryKey#ENCHANTMENT}.
+ *
+ * @apiNote The fields provided here are a direct representation of
+ * what is available from the vanilla game source. They may be
+ * changed (including removals) on any Minecraft version
+ * bump, so cross-version compatibility is not provided on the
+ * same level as it is on most of the other API.
+ */
+@SuppressWarnings({
+        "unused",
+        "SpellCheckingInspection"
+})
+@GeneratedFrom("1.21")
+@ApiStatus.Experimental
+public final class EnchantmentTagKeys {
+    /**
+     * {@code #minecraft:trades/swamp_special}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_SWAMP_SPECIAL = create(key("trades/swamp_special"));
+
+    /**
+     * {@code #minecraft:trades/plains_special}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_PLAINS_SPECIAL = create(key("trades/plains_special"));
+
+    /**
+     * {@code #minecraft:on_traded_equipment}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> ON_TRADED_EQUIPMENT = create(key("on_traded_equipment"));
+
+    /**
+     * {@code #minecraft:trades/desert_special}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_DESERT_SPECIAL = create(key("trades/desert_special"));
+
+    /**
+     * {@code #minecraft:prevents_ice_melting}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> PREVENTS_ICE_MELTING = create(key("prevents_ice_melting"));
+
+    /**
+     * {@code #minecraft:trades/taiga_common}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_TAIGA_COMMON = create(key("trades/taiga_common"));
+
+    /**
+     * {@code #minecraft:tradeable}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> TRADEABLE = create(key("tradeable"));
+
+    /**
+     * {@code #minecraft:curse}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> CURSE = create(key("curse"));
+
+    /**
+     * {@code #minecraft:treasure}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> TREASURE = create(key("treasure"));
+
+    /**
+     * {@code #minecraft:prevents_infested_spawns}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> PREVENTS_INFESTED_SPAWNS = create(key("prevents_infested_spawns"));
+
+    /**
+     * {@code #minecraft:trades/savanna_special}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_SAVANNA_SPECIAL = create(key("trades/savanna_special"));
+
+    /**
+     * {@code #minecraft:exclusive_set/riptide}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> EXCLUSIVE_SET_RIPTIDE = create(key("exclusive_set/riptide"));
+
+    /**
+     * {@code #minecraft:double_trade_price}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> DOUBLE_TRADE_PRICE = create(key("double_trade_price"));
+
+    /**
+     * {@code #minecraft:trades/taiga_special}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_TAIGA_SPECIAL = create(key("trades/taiga_special"));
+
+    /**
+     * {@code #minecraft:smelts_loot}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> SMELTS_LOOT = create(key("smelts_loot"));
+
+    /**
+     * {@code #minecraft:exclusive_set/boots}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> EXCLUSIVE_SET_BOOTS = create(key("exclusive_set/boots"));
+
+    /**
+     * {@code #minecraft:trades/plains_common}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_PLAINS_COMMON = create(key("trades/plains_common"));
+
+    /**
+     * {@code #minecraft:on_mob_spawn_equipment}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> ON_MOB_SPAWN_EQUIPMENT = create(key("on_mob_spawn_equipment"));
+
+    /**
+     * {@code #minecraft:trades/desert_common}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_DESERT_COMMON = create(key("trades/desert_common"));
+
+    /**
+     * {@code #minecraft:exclusive_set/mining}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> EXCLUSIVE_SET_MINING = create(key("exclusive_set/mining"));
+
+    /**
+     * {@code #minecraft:tooltip_order}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> TOOLTIP_ORDER = create(key("tooltip_order"));
+
+    /**
+     * {@code #minecraft:prevents_decorated_pot_shattering}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> PREVENTS_DECORATED_POT_SHATTERING = create(key("prevents_decorated_pot_shattering"));
+
+    /**
+     * {@code #minecraft:exclusive_set/bow}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> EXCLUSIVE_SET_BOW = create(key("exclusive_set/bow"));
+
+    /**
+     * {@code #minecraft:on_random_loot}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> ON_RANDOM_LOOT = create(key("on_random_loot"));
+
+    /**
+     * {@code #minecraft:exclusive_set/armor}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> EXCLUSIVE_SET_ARMOR = create(key("exclusive_set/armor"));
+
+    /**
+     * {@code #minecraft:trades/jungle_common}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_JUNGLE_COMMON = create(key("trades/jungle_common"));
+
+    /**
+     * {@code #minecraft:in_enchanting_table}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> IN_ENCHANTING_TABLE = create(key("in_enchanting_table"));
+
+    /**
+     * {@code #minecraft:trades/swamp_common}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_SWAMP_COMMON = create(key("trades/swamp_common"));
+
+    /**
+     * {@code #minecraft:trades/snow_special}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_SNOW_SPECIAL = create(key("trades/snow_special"));
+
+    /**
+     * {@code #minecraft:non_treasure}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> NON_TREASURE = create(key("non_treasure"));
+
+    /**
+     * {@code #minecraft:trades/jungle_special}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_JUNGLE_SPECIAL = create(key("trades/jungle_special"));
+
+    /**
+     * {@code #minecraft:prevents_bee_spawns_when_mining}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> PREVENTS_BEE_SPAWNS_WHEN_MINING = create(key("prevents_bee_spawns_when_mining"));
+
+    /**
+     * {@code #minecraft:exclusive_set/damage}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> EXCLUSIVE_SET_DAMAGE = create(key("exclusive_set/damage"));
+
+    /**
+     * {@code #minecraft:trades/savanna_common}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_SAVANNA_COMMON = create(key("trades/savanna_common"));
+
+    /**
+     * {@code #minecraft:trades/snow_common}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    @ApiStatus.Experimental
+    @MinecraftExperimental(MinecraftExperimental.Requires.TRADE_REBALANCE)
+    public static final TagKey<Enchantment> TRADES_SNOW_COMMON = create(key("trades/snow_common"));
+
+    /**
+     * {@code #minecraft:exclusive_set/crossbow}
+     *
+     * @apiNote This field is version-dependant and may be removed in future Minecraft versions
+     */
+    public static final TagKey<Enchantment> EXCLUSIVE_SET_CROSSBOW = create(key("exclusive_set/crossbow"));
+
+    private EnchantmentTagKeys() {
+    }
+
+    /**
+     * Creates a tag key for {@link Enchantment} in the registry {@code minecraft:root}.
+     *
+     * @param key the tag key's key
+     * @return a new tag key
+     */
+    @ApiStatus.Experimental
+    public static @NotNull TagKey<Enchantment> create(final @NotNull Key key) {
+        return TagKey.create(RegistryKey.ENCHANTMENT, key);
+    }
+}

paper-api-generator/src/main/java/io/papermc/generator/Generators.java

@@ -1,6 +1,7 @@
 package io.papermc.generator;
 
 import io.papermc.generator.types.GeneratedKeyType;
+import io.papermc.generator.types.GeneratedTagKeyType;
 import io.papermc.generator.types.SourceGenerator;
 import io.papermc.generator.types.goal.MobGoalGenerator;
 import io.papermc.paper.registry.RegistryKey;
@@ -15,6 +16,7 @@ import org.bukkit.enchantments.Enchantment;
 import org.bukkit.entity.Wolf;
 import org.bukkit.generator.structure.Structure;
 import org.bukkit.generator.structure.StructureType;
+import org.bukkit.inventory.ItemType;
 import org.bukkit.inventory.meta.trim.TrimMaterial;
 import org.bukkit.inventory.meta.trim.TrimPattern;
 import org.bukkit.potion.PotionEffectType;
@@ -33,10 +35,18 @@ public interface Generators {
         simpleKey("MobEffectKeys", PotionEffectType.class, Registries.MOB_EFFECT, RegistryKey.MOB_EFFECT, false),
         simpleKey("DamageTypeKeys", DamageType.class, Registries.DAMAGE_TYPE, RegistryKey.DAMAGE_TYPE, true),
         simpleKey("WolfVariantKeys", Wolf.Variant.class, Registries.WOLF_VARIANT, RegistryKey.WOLF_VARIANT, true),
+        simpleKey("ItemTypeKeys", ItemType.class, Registries.ITEM, RegistryKey.ITEM, false),
+
+        simpleTagKey("EnchantmentTagKeys", Enchantment.class, Registries.ENCHANTMENT, RegistryKey.ENCHANTMENT),
+        simpleTagKey("ItemTypeTagKeys", ItemType.class, Registries.ITEM, RegistryKey.ITEM),
         new MobGoalGenerator("VanillaGoal", "com.destroystokyo.paper.entity.ai")
     };
 
     private static <T, A> SourceGenerator simpleKey(final String className, final Class<A> apiType, final ResourceKey<? extends Registry<T>> registryKey, final RegistryKey<A> apiRegistryKey, final boolean publicCreateKeyMethod) {
         return new GeneratedKeyType<>(className, apiType, "io.papermc.paper.registry.keys", registryKey, apiRegistryKey, publicCreateKeyMethod);
     }
+
+    private static <T, A> SourceGenerator simpleTagKey(final String className, final Class<A> apiType, final ResourceKey<? extends Registry<T>> registryKey, final RegistryKey<A> apiRegistryKey) {
+        return new GeneratedTagKeyType<>(className, apiType, "io.papermc.paper.registry.keys.tags", registryKey, apiRegistryKey, true);
+    }
 }

paper-api-generator/src/main/java/io/papermc/generator/Main.java

@@ -1,22 +1,29 @@
 package io.papermc.generator;
 
+import com.google.common.util.concurrent.MoreExecutors;
 import com.mojang.logging.LogUtils;
 import io.papermc.generator.types.SourceGenerator;
+import io.papermc.generator.utils.TagCollector;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.Map;
 import net.minecraft.SharedConstants;
+import net.minecraft.commands.Commands;
 import net.minecraft.core.LayeredRegistryAccess;
 import net.minecraft.core.RegistryAccess;
 import net.minecraft.resources.RegistryDataLoader;
 import net.minecraft.server.Bootstrap;
 import net.minecraft.server.RegistryLayer;
+import net.minecraft.server.ReloadableServerResources;
 import net.minecraft.server.WorldLoader;
 import net.minecraft.server.packs.PackType;
 import net.minecraft.server.packs.repository.Pack;
 import net.minecraft.server.packs.repository.PackRepository;
 import net.minecraft.server.packs.repository.ServerPacksSource;
 import net.minecraft.server.packs.resources.MultiPackResourceManager;
+import net.minecraft.tags.TagKey;
+import net.minecraft.world.flag.FeatureFlags;
 import org.apache.commons.io.file.PathUtils;
 import org.slf4j.Logger;
 
@@ -24,6 +31,7 @@ public final class Main {
 
     private static final Logger LOGGER = LogUtils.getLogger();
     public static final RegistryAccess.Frozen REGISTRY_ACCESS;
+    public static final Map<TagKey<?>, String> EXPERIMENTAL_TAGS;
 
     static {
         SharedConstants.tryDetectVersion();
@@ -36,6 +44,10 @@ public final class Main {
         LayeredRegistryAccess<RegistryLayer> layers = RegistryLayer.createRegistryAccess();
         layers = WorldLoader.loadAndReplaceLayer(resourceManager, layers, RegistryLayer.WORLDGEN, RegistryDataLoader.WORLDGEN_REGISTRIES);
         REGISTRY_ACCESS = layers.compositeAccess().freeze();
+        final ReloadableServerResources datapack = ReloadableServerResources.loadResources(resourceManager, layers, FeatureFlags.REGISTRY.allFlags(), Commands.CommandSelection.DEDICATED, 0, MoreExecutors.directExecutor(), MoreExecutors.directExecutor()).join();
+        datapack.updateRegistryTags();
+
+        EXPERIMENTAL_TAGS = TagCollector.grabExperimental(resourceManager);
     }
 
     private Main() {

paper-api-generator/src/main/java/io/papermc/generator/types/GeneratedTagKeyType.java

@@ -0,0 +1,149 @@
+package io.papermc.generator.types;
+
+import com.squareup.javapoet.FieldSpec;
+import com.squareup.javapoet.JavaFile;
+import com.squareup.javapoet.MethodSpec;
+import com.squareup.javapoet.ParameterSpec;
+import com.squareup.javapoet.ParameterizedTypeName;
+import com.squareup.javapoet.TypeName;
+import com.squareup.javapoet.TypeSpec;
+import io.papermc.generator.Main;
+import io.papermc.generator.utils.Annotations;
+import io.papermc.generator.utils.Formatting;
+import io.papermc.generator.utils.Javadocs;
+import io.papermc.paper.registry.RegistryKey;
+import io.papermc.paper.registry.tag.TagKey;
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.stream.Collectors;
+import net.kyori.adventure.key.Key;
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistrySetBuilder;
+import net.minecraft.data.registries.VanillaRegistries;
+import net.minecraft.resources.ResourceKey;
+import org.bukkit.MinecraftExperimental;
+
+import static com.squareup.javapoet.TypeSpec.classBuilder;
+import static io.papermc.generator.utils.Annotations.EXPERIMENTAL_API_ANNOTATION;
+import static io.papermc.generator.utils.Annotations.NOT_NULL;
+import static io.papermc.generator.utils.Annotations.experimentalAnnotations;
+import static java.util.Objects.requireNonNull;
+import static javax.lang.model.element.Modifier.FINAL;
+import static javax.lang.model.element.Modifier.PRIVATE;
+import static javax.lang.model.element.Modifier.PUBLIC;
+import static javax.lang.model.element.Modifier.STATIC;
+
+public class GeneratedTagKeyType<T, A> extends SimpleGenerator {
+
+    private static final Map<ResourceKey<? extends Registry<?>>, RegistrySetBuilder.RegistryBootstrap<?>> VANILLA_REGISTRY_ENTRIES = VanillaRegistries.BUILDER.entries.stream()
+        .collect(Collectors.toMap(RegistrySetBuilder.RegistryStub::key, RegistrySetBuilder.RegistryStub::bootstrap));
+
+    private static final Map<ResourceKey<? extends Registry<?>>, RegistrySetBuilder.RegistryBootstrap<?>> EXPERIMENTAL_REGISTRY_ENTRIES = Collections.emptyMap(); // Update for Experimental API
+
+    private static final Map<RegistryKey<?>, String> REGISTRY_KEY_FIELD_NAMES;
+    static {
+        final Map<RegistryKey<?>, String> map = new HashMap<>();
+        try {
+            for (final Field field : RegistryKey.class.getFields()) {
+                if (!Modifier.isStatic(field.getModifiers()) || !Modifier.isFinal(field.getModifiers()) || field.getType() != RegistryKey.class) {
+                    continue;
+                }
+                map.put((RegistryKey<?>) field.get(null), field.getName());
+            }
+            REGISTRY_KEY_FIELD_NAMES = Map.copyOf(map);
+        } catch (final ReflectiveOperationException ex) {
+            throw new RuntimeException(ex);
+        }
+    }
+
+    private static final String CREATE_JAVADOC = """
+        Creates a tag key for {@link $T} in the registry {@code $L}.
+        
+        @param key the tag key's key
+        @return a new tag key
+        """;
+
+    private final Class<A> apiType;
+    private final ResourceKey<? extends Registry<T>> registryKey;
+    private final RegistryKey<A> apiRegistryKey;
+    private final boolean publicCreateKeyMethod;
+
+    public GeneratedTagKeyType(final String keysClassName, final Class<A> apiType, final String pkg, final ResourceKey<? extends Registry<T>> registryKey, final RegistryKey<A> apiRegistryKey, final boolean publicCreateKeyMethod) {
+        super(keysClassName, pkg);
+        this.apiType = apiType;
+        this.registryKey = registryKey;
+        this.apiRegistryKey = apiRegistryKey;
+        this.publicCreateKeyMethod = publicCreateKeyMethod;
+    }
+
+    private MethodSpec.Builder createMethod(final TypeName returnType) {
+        final TypeName keyType = TypeName.get(Key.class).annotated(NOT_NULL);
+
+        final ParameterSpec keyParam = ParameterSpec.builder(keyType, "key", FINAL).build();
+        final MethodSpec.Builder create = MethodSpec.methodBuilder("create")
+            .addModifiers(this.publicCreateKeyMethod ? PUBLIC : PRIVATE, STATIC)
+            .addParameter(keyParam)
+            .addCode("return $T.create($T.$L, $N);", TagKey.class, RegistryKey.class, requireNonNull(REGISTRY_KEY_FIELD_NAMES.get(this.apiRegistryKey), "Missing field for " + this.apiRegistryKey), keyParam)
+            .returns(returnType.annotated(NOT_NULL));
+        if (this.publicCreateKeyMethod) {
+            create.addAnnotation(EXPERIMENTAL_API_ANNOTATION); // TODO remove once not experimental
+            create.addJavadoc(CREATE_JAVADOC, this.apiType, this.registryKey.registry().toString());
+        }
+        return create;
+    }
+
+    private TypeSpec.Builder keyHolderType() {
+        return classBuilder(this.className)
+            .addModifiers(PUBLIC, FINAL)
+            .addJavadoc(Javadocs.getVersionDependentClassHeader("{@link $T#$L}"), RegistryKey.class, REGISTRY_KEY_FIELD_NAMES.get(this.apiRegistryKey))
+            .addAnnotations(Annotations.CLASS_HEADER)
+            .addMethod(MethodSpec.constructorBuilder()
+                           .addModifiers(PRIVATE)
+                           .build()
+            );
+    }
+
+    @Override
+    protected TypeSpec getTypeSpec() {
+        final TypeName tagKey = ParameterizedTypeName.get(TagKey.class, this.apiType);
+
+        final TypeSpec.Builder typeBuilder = this.keyHolderType();
+        final MethodSpec.Builder createMethod = this.createMethod(tagKey);
+
+        final Registry<T> registry = Main.REGISTRY_ACCESS.registryOrThrow(this.registryKey);
+
+        final AtomicBoolean allExperimental = new AtomicBoolean(true);
+        registry.getTags().forEach(pair -> {
+            final net.minecraft.tags.TagKey<T> nmsTagKey = pair.getFirst();
+            final String fieldName = Formatting.formatKeyAsField(nmsTagKey.location().getPath());
+            final FieldSpec.Builder fieldBuilder = FieldSpec.builder(tagKey, fieldName, PUBLIC, STATIC, FINAL)
+                .initializer("$N(key($S))", createMethod.build(), nmsTagKey.location().getPath())
+                .addJavadoc(Javadocs.getVersionDependentField("{@code $L}"), "#" + nmsTagKey.location());
+            if (Main.EXPERIMENTAL_TAGS.containsKey(nmsTagKey)) {
+                fieldBuilder.addAnnotations(experimentalAnnotations(MinecraftExperimental.Requires.TRADE_REBALANCE)); // Update for Experimental API
+            } else {
+                allExperimental.set(false);
+            }
+            typeBuilder.addField(fieldBuilder.build());
+        });
+        if (allExperimental.get()) {
+            typeBuilder.addAnnotations(experimentalAnnotations(null)); // Update for Experimental API
+            createMethod.addAnnotations(experimentalAnnotations(null)); // Update for Experimental API
+        } else {
+            typeBuilder.addAnnotation(EXPERIMENTAL_API_ANNOTATION); // TODO experimental API
+        }
+        return typeBuilder.addMethod(createMethod.build()).build();
+    }
+
+    @Override
+    protected JavaFile.Builder file(final JavaFile.Builder builder) {
+        return builder
+            .skipJavaLangImports(true)
+            .addStaticImport(Key.class, "key")
+            .indent("    ");
+    }
+}

paper-api-generator/src/main/java/io/papermc/generator/utils/Formatting.java

@@ -1,5 +1,6 @@
 package io.papermc.generator.utils;
 
+import java.util.Optional;
 import org.apache.commons.lang3.math.NumberUtils;
 import java.util.Comparator;
 import java.util.Locale;
@@ -15,6 +16,15 @@ public final class Formatting {
         return ILLEGAL_FIELD_CHARACTERS.matcher(path.toUpperCase(Locale.ROOT)).replaceAll("_");
     }
 
+    public static Optional<String> formatTagKey(String tagDir, String resourcePath) {
+        int tagsIndex = resourcePath.indexOf(tagDir);
+        int dotIndex = resourcePath.lastIndexOf('.');
+        if (tagsIndex == -1 || dotIndex == -1) {
+            return Optional.empty();
+        }
+        return Optional.of(resourcePath.substring(tagsIndex + tagDir.length() + 1, dotIndex)); // namespace/tags/registry_key/[tag_key].json
+    }
+
     public static Comparator<String> ALPHABETIC_KEY_ORDER = alphabeticKeyOrder(path -> path);
 
     public static <T> Comparator<T> alphabeticKeyOrder(Function<T, String> mapper) {

paper-api-generator/src/main/java/io/papermc/generator/utils/TagCollector.java

@@ -0,0 +1,81 @@
+package io.papermc.generator.utils;
+
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.Multimap;
+import com.mojang.logging.LogUtils;
+import io.papermc.generator.Main;
+import io.papermc.generator.utils.Formatting;
+import java.util.Collections;
+import java.util.IdentityHashMap;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.BiConsumer;
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.server.packs.PackResources;
+import net.minecraft.server.packs.PackType;
+import net.minecraft.server.packs.repository.BuiltInPackSource;
+import net.minecraft.server.packs.resources.MultiPackResourceManager;
+import net.minecraft.tags.TagKey;
+import net.minecraft.tags.TagManager;
+import org.slf4j.Logger;
+
+// collect all the tags by grabbing the json from the data-packs
+// another (probably) way is to hook into the data generator like the typed keys generator
+public final class TagCollector {
+
+    private static final Logger LOGGER = LogUtils.getLogger();
+
+    public static Map<TagKey<?>, String> grabExperimental(final MultiPackResourceManager resourceManager) {
+        Map<TagKey<?>, String> result = new IdentityHashMap<>();
+
+        // collect all vanilla tags
+        Multimap<ResourceKey<? extends Registry<?>>, String> vanillaTags = HashMultimap.create();
+        PackResources vanillaPack = resourceManager.listPacks()
+            .filter(packResources -> packResources.packId().equals(BuiltInPackSource.VANILLA_ID))
+            .findFirst()
+            .orElseThrow();
+        collectFromPack(vanillaPack, (entry, path) -> vanillaTags.put(entry.key(), path));
+
+        // then distinct with other data-pack tags to know for sure newly created tags and so experimental one
+        resourceManager.listPacks().forEach(pack -> {
+            String packId = pack.packId();
+            if (packId.equals(BuiltInPackSource.VANILLA_ID)) return;
+
+            collectFromPack(pack, (entry, path) -> {
+                if (vanillaTags.get(entry.key()).contains(path)) {
+                    return;
+                }
+
+                result.put(entry.value().getTagNames()
+                               .filter(tagKey -> tagKey.location().getPath().equals(path))
+                               .findFirst()
+                               .orElseThrow(), packId);
+            });
+        });
+        return Collections.unmodifiableMap(result);
+    }
+
+    private static void collectFromPack(PackResources pack, BiConsumer<RegistryAccess.RegistryEntry<?>, String> output) {
+        Set<String> namespaces = pack.getNamespaces(PackType.SERVER_DATA);
+
+        for (String namespace : namespaces) {
+            Main.REGISTRY_ACCESS.registries().forEach(entry -> {
+                // this is probably expensive but can't find another way around and data-pack loader has similar logic
+                // the issue is that registry key can have parent/key (and custom folder too) but tag key can also have parent/key so parsing become a mess
+                // without having at least one of the two values
+                String tagDir = Registries.tagsDirPath(entry.key());
+                pack.listResources(PackType.SERVER_DATA, namespace, tagDir, (id, supplier) -> {
+                    Formatting.formatTagKey(tagDir, id.getPath()).ifPresentOrElse(path -> output.accept(entry, path), () -> {
+                        LOGGER.warn("Unable to parse the path: {}/{}/{}.json in the data-pack {} into a tag key", namespace, tagDir, id.getPath(), pack.packId());
+                    });
+                });
+            });
+        }
+    }
+
+    private TagCollector() {
+    }
+}