@Nonnull
        @Override
        public Optional<MetadataMap> get(@Nonnull Player player) {
            Objects.requireNonNull(player, "player");
            return get(player.getUniqueId());
        }
The Metadata registries provided by helper.

These instances can be accessed through {@link Metadata}.
helper/src/main/java/me/lucko/helper/metadata/StandardMetadataRegistries.java