private boolean processMetadata(Player p) {
        return !Metadata.provideForPlayer(p).putIfAbsent(RECENT_NPC_CLICK_KEY, ExpiringValue.of(true, 100, TimeUnit.MILLISECONDS));
    }
Implementation of {@link NpcFactory} using Citizens.
helper/src/main/java/me/lucko/helper/npc/CitizensNpcFactory.java