addToExistingTags
fun <T : Keyed> LifecycleEventManager<BootstrapContext>.addToExistingTags(registry: RegistryKey<T>, entriesByTag: Provider<Map<TagKey<T>, Set<TagEntry<T>>>>, priority: Int = -1)
Adds the entries in entriesByTag to their corresponding tags during pre-flatten if they exist. Does not create new tags. Non-existent tags are ignored. Changes to entriesByTag cause a data reload.