WorldTypes are ENGINE scoped.
import org.spongepowered.api.Sponge;
import org.spongepowered.api.registry.DefaultedRegistryReference;
import org.spongepowered.api.registry.RegistryKey;
+import org.spongepowered.api.registry.RegistryScope;
+import org.spongepowered.api.registry.RegistryScopes;
import org.spongepowered.api.registry.RegistryTypes;
+@RegistryScopes(scopes = RegistryScope.ENGINE)
public final class WorldTypes {
// @formatter:off
