From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Wed, 29 May 2024 19:50:21 -0700
Subject: [PATCH] Add FeatureFlag API


diff --git a/src/main/java/io/papermc/paper/world/flag/PaperFeatureDependent.java b/src/main/java/io/papermc/paper/world/flag/PaperFeatureDependent.java
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
--- /dev/null
+++ b/src/main/java/io/papermc/paper/world/flag/PaperFeatureDependent.java
@@ -0,0 +0,0 @@
+package io.papermc.paper.world.flag;
+
+import java.util.Set;
+import net.minecraft.world.flag.FeatureElement;
+import org.bukkit.FeatureFlag;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.jetbrains.annotations.Unmodifiable;
+
+public interface PaperFeatureDependent extends FeatureDependant {
+
+    <M extends FeatureElement> M getHandle();
+
+    @Override
+    default @Unmodifiable @NonNull Set<FeatureFlag> requiredFeatures() {
+        return PaperFeatureFlagProviderImpl.fromNms(this.getHandle().requiredFeatures());
+    }
+}
diff --git a/src/main/java/io/papermc/paper/world/flag/PaperFeatureFlagProviderImpl.java b/src/main/java/io/papermc/paper/world/flag/PaperFeatureFlagProviderImpl.java
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
--- /dev/null
+++ b/src/main/java/io/papermc/paper/world/flag/PaperFeatureFlagProviderImpl.java
@@ -0,0 +0,0 @@
+package io.papermc.paper.world.flag;
+
+import com.google.common.collect.BiMap;
+import com.google.common.collect.ImmutableBiMap;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import net.minecraft.world.flag.FeatureElement;
+import net.minecraft.world.flag.FeatureFlagSet;
+import net.minecraft.world.flag.FeatureFlags;
+import org.bukkit.FeatureFlag;
+import org.bukkit.craftbukkit.entity.CraftEntityType;
+import org.bukkit.craftbukkit.entity.CraftEntityTypes;
+import org.bukkit.craftbukkit.potion.CraftPotionType;
+import org.bukkit.craftbukkit.util.CraftMagicNumbers;
+import org.bukkit.entity.EntityType;
+import org.bukkit.potion.PotionType;
+
+public class PaperFeatureFlagProviderImpl implements FeatureFlagProvider {
+
+    public static final BiMap<FeatureFlag, net.minecraft.world.flag.FeatureFlag> FLAGS = ImmutableBiMap.of(
+        FeatureFlag.VANILLA, FeatureFlags.VANILLA,
+        FeatureFlag.TRADE_REBALANCE, FeatureFlags.TRADE_REBALANCE,
+        FeatureFlag.MINECART_IMPROVEMENTS, FeatureFlags.MINECART_IMPROVEMENTS,
+        FeatureFlag.REDSTONE_EXPERIMENTS, FeatureFlags.REDSTONE_EXPERIMENTS,
+        FeatureFlag.WINTER_DROP, FeatureFlags.WINTER_DROP
+    );
+
+    @Override
+    public Set<FeatureFlag> requiredFeatures(final FeatureDependant dependant) {
+        final FeatureFlagSet requiredFeatures = getFeatureElement(dependant).requiredFeatures();
+        return fromNms(requiredFeatures);
+    }
+
+    public static Set<FeatureFlag> fromNms(final FeatureFlagSet flagSet) {
+        final Set<FeatureFlag> flags = new HashSet<>();
+        for (final net.minecraft.world.flag.FeatureFlag nmsFlag : FeatureFlags.REGISTRY.names.values()) {
+            if (flagSet.contains(nmsFlag)) {
+                flags.add(FLAGS.inverse().get(nmsFlag));
+            }
+        }
+        return Collections.unmodifiableSet(flags);
+    }
+
+    static FeatureElement getFeatureElement(final FeatureDependant dependant) {
+        if (dependant instanceof final EntityType entityType) {
+            // TODO remove when EntityType is server-backed
+            return CraftEntityType.bukkitToMinecraft(entityType);
+        } else if (dependant instanceof final PotionType potionType) {
+            return CraftPotionType.bukkitToMinecraft(potionType);
+        } else {
+            throw new IllegalArgumentException(dependant + " is not a valid feature dependant");
+        }
+    }
+}
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftFeatureFlag.java b/src/main/java/org/bukkit/craftbukkit/CraftFeatureFlag.java
deleted file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
--- a/src/main/java/org/bukkit/craftbukkit/CraftFeatureFlag.java
+++ /dev/null
@@ -0,0 +0,0 @@
-package org.bukkit.craftbukkit;
-
-import java.util.HashSet;
-import java.util.Set;
-import net.minecraft.resources.ResourceLocation;
-import net.minecraft.world.flag.FeatureFlagSet;
-import net.minecraft.world.flag.FeatureFlags;
-import org.bukkit.FeatureFlag;
-import org.bukkit.NamespacedKey;
-import org.bukkit.craftbukkit.util.CraftNamespacedKey;
-import org.jetbrains.annotations.NotNull;
-
-public class CraftFeatureFlag implements FeatureFlag {
-
-    private final NamespacedKey namespacedKey;
-    private final net.minecraft.world.flag.FeatureFlag featureFlag;
-
-    public CraftFeatureFlag(ResourceLocation minecraftKey, net.minecraft.world.flag.FeatureFlag featureFlag) {
-        this.namespacedKey = CraftNamespacedKey.fromMinecraft(minecraftKey);
-        this.featureFlag = featureFlag;
-    }
-
-    public net.minecraft.world.flag.FeatureFlag getHandle() {
-        return this.featureFlag;
-    }
-
-    @NotNull
-    @Override
-    public NamespacedKey getKey() {
-        return this.namespacedKey;
-    }
-
-    @Override
-    public String toString() {
-        return "CraftFeatureFlag{key=" + this.getKey() + ",keyUniverse=" + this.getHandle().universe.toString() + "}";
-    }
-
-    public static Set<CraftFeatureFlag> getFromNMS(FeatureFlagSet featureFlagSet) {
-        Set<CraftFeatureFlag> set = new HashSet<>();
-        FeatureFlags.REGISTRY.names.forEach((minecraftkey, featureflag) -> {
-            if (featureFlagSet.contains(featureflag)) {
-                set.add(new CraftFeatureFlag(minecraftkey, featureflag));
-            }
-        });
-        return set;
-    }
-
-    public static CraftFeatureFlag getFromNMS(NamespacedKey namespacedKey) {
-        return FeatureFlags.REGISTRY.names.entrySet().stream().filter(entry -> CraftNamespacedKey.fromMinecraft(entry.getKey()).equals(namespacedKey)).findFirst().map(entry -> new CraftFeatureFlag(entry.getKey(), entry.getValue())).orElse(null);
-    }
-}
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftRegionAccessor.java b/src/main/java/org/bukkit/craftbukkit/CraftRegionAccessor.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftRegionAccessor.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftRegionAccessor.java
@@ -0,0 +0,0 @@ public abstract class CraftRegionAccessor implements RegionAccessor {
         return !this.getHandle().noCollision(aabb);
     }
     // Paper end
+
+    // Paper start - feature flag API
+    @Override
+    public java.util.Set<org.bukkit.FeatureFlag> getFeatureFlags() {
+        return io.papermc.paper.world.flag.PaperFeatureFlagProviderImpl.fromNms(this.getHandle().enabledFeatures());
+    }
+    // Paper end - feature flag API
 }
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
@@ -0,0 +0,0 @@ public class CraftWorld extends CraftRegionAccessor implements World {
         return this.persistentDataContainer;
     }
 
-    @Override
-    public Set<FeatureFlag> getFeatureFlags() {
-        return CraftFeatureFlag.getFromNMS(this.getHandle().enabledFeatures()).stream().map(FeatureFlag.class::cast).collect(Collectors.toUnmodifiableSet());
-    }
+    // Paper - replace feature flag API
 
     public void storeBukkitValues(CompoundTag c) {
         if (!this.persistentDataContainer.isEmpty()) {
diff --git a/src/main/java/org/bukkit/craftbukkit/block/CraftBlockType.java b/src/main/java/org/bukkit/craftbukkit/block/CraftBlockType.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/block/CraftBlockType.java
+++ b/src/main/java/org/bukkit/craftbukkit/block/CraftBlockType.java
@@ -0,0 +0,0 @@ import org.bukkit.craftbukkit.util.Handleable;
 import org.bukkit.inventory.ItemType;
 import org.jetbrains.annotations.NotNull;
 
-public class CraftBlockType<B extends BlockData> implements BlockType.Typed<B>, Handleable<Block> {
+public class CraftBlockType<B extends BlockData> implements BlockType.Typed<B>, Handleable<Block>, io.papermc.paper.world.flag.PaperFeatureDependent { // Paper - feature flag API
 
     private final NamespacedKey key;
     private final Block block;
diff --git a/src/main/java/org/bukkit/craftbukkit/generator/CraftWorldInfo.java b/src/main/java/org/bukkit/craftbukkit/generator/CraftWorldInfo.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/generator/CraftWorldInfo.java
+++ b/src/main/java/org/bukkit/craftbukkit/generator/CraftWorldInfo.java
@@ -0,0 +0,0 @@ public class CraftWorldInfo implements WorldInfo {
     private final long seed;
     private final int minHeight;
     private final int maxHeight;
+    private final net.minecraft.world.flag.FeatureFlagSet enabledFeatures; // Paper - feature flag API
     // Paper start
     private final net.minecraft.world.level.chunk.ChunkGenerator vanillaChunkGenerator;
     private final net.minecraft.core.RegistryAccess.Frozen registryAccess;
@@ -0,0 +0,0 @@ public class CraftWorldInfo implements WorldInfo {
         this.seed = ((PrimaryLevelData) worldDataServer).worldGenOptions().seed();
         this.minHeight = dimensionManager.minY();
         this.maxHeight = dimensionManager.minY() + dimensionManager.height();
+        this.enabledFeatures = worldDataServer.enabledFeatures(); // Paper - feature flag API
     }
 
     @Override
@@ -0,0 +0,0 @@ public class CraftWorldInfo implements WorldInfo {
         };
     }
     // Paper end
+
+    // Paper start - feature flag API
+    @Override
+    public java.util.Set<org.bukkit.FeatureFlag> getFeatureFlags() {
+        return io.papermc.paper.world.flag.PaperFeatureFlagProviderImpl.fromNms(this.enabledFeatures);
+    }
+    // Paper end - feature flag API
 }
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemType.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemType.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemType.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemType.java
@@ -0,0 +0,0 @@ import org.bukkit.inventory.meta.ItemMeta;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-public class CraftItemType<M extends ItemMeta> implements ItemType.Typed<M>, Handleable<Item> {
+public class CraftItemType<M extends ItemMeta> implements ItemType.Typed<M>, Handleable<Item>, io.papermc.paper.world.flag.PaperFeatureDependent { // Paper - feature flag API
 
     private final NamespacedKey key;
     private final Item item;
diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMenuType.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMenuType.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMenuType.java
+++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMenuType.java
@@ -0,0 +0,0 @@ import org.bukkit.entity.HumanEntity;
 import org.bukkit.inventory.InventoryView;
 import org.bukkit.inventory.MenuType;
 
-public class CraftMenuType<V extends InventoryView> implements MenuType.Typed<V>, Handleable<net.minecraft.world.inventory.MenuType<?>> {
+public class CraftMenuType<V extends InventoryView> implements MenuType.Typed<V>, Handleable<net.minecraft.world.inventory.MenuType<?>>, io.papermc.paper.world.flag.PaperFeatureDependent { // Paper - make FeatureDependant
 
     private final NamespacedKey key;
     private final net.minecraft.world.inventory.MenuType<?> handle;
diff --git a/src/main/java/org/bukkit/craftbukkit/packs/CraftDataPack.java b/src/main/java/org/bukkit/craftbukkit/packs/CraftDataPack.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/packs/CraftDataPack.java
+++ b/src/main/java/org/bukkit/craftbukkit/packs/CraftDataPack.java
@@ -0,0 +0,0 @@ import net.minecraft.util.InclusiveRange;
 import org.bukkit.Bukkit;
 import org.bukkit.FeatureFlag;
 import org.bukkit.NamespacedKey;
-import org.bukkit.craftbukkit.CraftFeatureFlag;
+// import org.bukkit.craftbukkit.CraftFeatureFlag; // Paper - replace feature flag API
 import org.bukkit.craftbukkit.CraftServer;
 import org.bukkit.craftbukkit.util.CraftChatMessage;
 import org.bukkit.packs.DataPack;
@@ -0,0 +0,0 @@ public class CraftDataPack implements DataPack {
 
     @Override
     public Set<FeatureFlag> getRequestedFeatures() {
-        return CraftFeatureFlag.getFromNMS(this.getHandle().getRequestedFeatures()).stream().map(FeatureFlag.class::cast).collect(Collectors.toUnmodifiableSet());
+        return io.papermc.paper.world.flag.PaperFeatureFlagProviderImpl.fromNms(this.getHandle().getRequestedFeatures()); // Paper - replace feature flag API
     }
 
     @Override
diff --git a/src/main/java/org/bukkit/craftbukkit/potion/CraftPotionEffectType.java b/src/main/java/org/bukkit/craftbukkit/potion/CraftPotionEffectType.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/potion/CraftPotionEffectType.java
+++ b/src/main/java/org/bukkit/craftbukkit/potion/CraftPotionEffectType.java
@@ -0,0 +0,0 @@ import org.bukkit.potion.PotionEffectType;
 import org.bukkit.potion.PotionEffectTypeCategory;
 import org.jetbrains.annotations.NotNull;
 
-public class CraftPotionEffectType extends PotionEffectType implements Handleable<MobEffect> {
+public class CraftPotionEffectType extends PotionEffectType implements Handleable<MobEffect>, io.papermc.paper.world.flag.PaperFeatureDependent { // Paper - feature flag API
 
     public static PotionEffectType minecraftHolderToBukkit(Holder<MobEffect> minecraft) {
         return CraftPotionEffectType.minecraftToBukkit(minecraft.value());
diff --git a/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java b/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
+++ b/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
@@ -0,0 +0,0 @@ import org.bukkit.advancement.Advancement;
 import org.bukkit.attribute.Attribute;
 import org.bukkit.attribute.AttributeModifier;
 import org.bukkit.block.data.BlockData;
-import org.bukkit.craftbukkit.CraftFeatureFlag;
+// import org.bukkit.craftbukkit.CraftFeatureFlag; // Paper
 import org.bukkit.craftbukkit.CraftRegistry;
 import org.bukkit.craftbukkit.CraftServer;
 import org.bukkit.craftbukkit.attribute.CraftAttribute;
@@ -0,0 +0,0 @@ public final class CraftMagicNumbers implements UnsafeValues {
         return CraftAttribute.bukkitToMinecraft(attribute).getDescriptionId();
     }
 
-    @Override
-    public FeatureFlag getFeatureFlag(NamespacedKey namespacedKey) {
-        Preconditions.checkArgument(namespacedKey != null, "NamespaceKey cannot be null");
-        return CraftFeatureFlag.getFromNMS(namespacedKey);
-    }
+    // Paper - replace feature flag API
 
     @Override
     public PotionType.InternalPotionData getInternalPotionData(NamespacedKey namespacedKey) {
diff --git a/src/main/resources/META-INF/services/io.papermc.paper.world.flag.FeatureFlagProvider b/src/main/resources/META-INF/services/io.papermc.paper.world.flag.FeatureFlagProvider
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
--- /dev/null
+++ b/src/main/resources/META-INF/services/io.papermc.paper.world.flag.FeatureFlagProvider
@@ -0,0 +1 @@
+io.papermc.paper.world.flag.PaperFeatureFlagProviderImpl
diff --git a/src/main/resources/META-INF/services/io.papermc.paper.world.flag.FeatureFlags$FeatureFlagProvider b/src/main/resources/META-INF/services/io.papermc.paper.world.flag.FeatureFlags$FeatureFlagProvider
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
--- /dev/null
+++ b/src/main/resources/META-INF/services/io.papermc.paper.world.flag.FeatureFlags$FeatureFlagProvider
@@ -0,0 +1 @@
+io.papermc.paper.world.flag.PaperFeatureFlagProviderImpl
diff --git a/src/test/java/io/papermc/paper/world/flag/FeatureFlagTest.java b/src/test/java/io/papermc/paper/world/flag/FeatureFlagTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
--- /dev/null
+++ b/src/test/java/io/papermc/paper/world/flag/FeatureFlagTest.java
@@ -0,0 +0,0 @@
+package io.papermc.paper.world.flag;
+
+import io.papermc.paper.adventure.PaperAdventure;
+import io.papermc.paper.registry.PaperRegistries;
+import io.papermc.paper.registry.RegistryAccess;
+import io.papermc.paper.registry.RegistryKey;
+import io.papermc.paper.registry.entry.RegistryEntry;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.stream.Stream;
+import net.kyori.adventure.key.Key;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.flag.FeatureElement;
+import net.minecraft.world.flag.FeatureFlagSet;
+import net.minecraft.world.flag.FeatureFlags;
+import org.bukkit.FeatureFlag;
+import org.bukkit.Keyed;
+import org.bukkit.support.RegistryHelper;
+import org.bukkit.support.environment.AllFeatures;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.fail;
+
+@AllFeatures
+class FeatureFlagTest {
+
+    @Test
+    void testFeatureFlagParity() {
+        final Set<ResourceLocation> locations = new HashSet<>();
+        for (final FeatureFlag flag : FeatureFlag.ALL_FLAGS.values()) {
+            locations.add(PaperAdventure.asVanilla(flag.getKey()));
+        }
+        FeatureFlags.REGISTRY.fromNames(locations, unknown -> {
+            fail("Unknown api feature flag: " + unknown);
+        });
+
+        for (final ResourceLocation nmsFlag : allNames()) {
+            assertNotNull(FeatureFlag.ALL_FLAGS.value(Key.key(nmsFlag.toString())), "can't find api flag for " + nmsFlag);
+        }
+    }
+
+    @Test
+    void testFeatureFlagConversion() {
+        assertEquals(allNames().size(), PaperFeatureFlagProviderImpl.FLAGS.size());
+        for (final FeatureFlag featureFlag : PaperFeatureFlagProviderImpl.FLAGS.keySet()) {
+            final net.minecraft.world.flag.FeatureFlag nmsFlag = PaperFeatureFlagProviderImpl.FLAGS.get(featureFlag);
+            final ResourceLocation nmsFlagName = FeatureFlags.REGISTRY.toNames(FeatureFlagSet.of(nmsFlag)).iterator().next();
+            assertEquals(nmsFlagName.toString(), featureFlag.key().asString());
+        }
+    }
+
+    static Set<ResourceLocation> allNames() {
+        return FeatureFlags.REGISTRY.toNames(FeatureFlags.REGISTRY.allFlags());
+    }
+
+    @SuppressWarnings({"rawtypes", "unchecked"})
+    static Set<RegistryKey<?>> featureFilteredRegistries() {
+        final Set<RegistryKey<?>> registryKeys = new HashSet<>();
+        for (final ResourceKey filteredRegistry : FeatureElement.FILTERED_REGISTRIES) {
+            registryKeys.add(PaperRegistries.registryFromNms(filteredRegistry));
+        }
+        return registryKeys;
+    }
+
+    @MethodSource("featureFilteredRegistries")
+    @ParameterizedTest
+    <T extends Keyed> void testApiImplementsFeatureDependant(final RegistryKey<T> registryKey) {
+        final org.bukkit.Registry<T> registry = RegistryAccess.registryAccess().getRegistry(registryKey);
+        final T anyElement = registry.iterator().next();
+        assertInstanceOf(FeatureDependant.class, anyElement, "Registry " + registryKey + " doesn't have feature dependent elements");
+        final FeatureDependant dependant = ((FeatureDependant) anyElement);
+        assertDoesNotThrow(dependant::requiredFeatures, "Failed to get required features for " + anyElement + " in " + registryKey);
+    }
+
+    static Stream<RegistryKey<?>> nonFeatureFilteredRegistries() {
+        return RegistryHelper.getRegistry().registries().filter(r -> {
+            final RegistryEntry<?, ?> entry = PaperRegistries.getEntry(r.key());
+            // has an API registry and isn't a filtered registry
+            return entry != null && !FeatureElement.FILTERED_REGISTRIES.contains(r.key());
+        }).map(r -> PaperRegistries.getEntry(r.key()).apiKey());
+    }
+
+
+    @MethodSource("nonFeatureFilteredRegistries")
+    @ParameterizedTest
+    <T extends Keyed> void testApiDoesntImplementFeatureDependant(final RegistryKey<T> registryKey) {
+        final org.bukkit.Registry<T> registry = RegistryAccess.registryAccess().getRegistry(registryKey);
+        final T anyElement = registry.iterator().next();
+        assertFalse(anyElement instanceof FeatureDependant, "Registry " + registryKey + " has feature dependent elements");
+    }
+}
