HookManager.addPlaceholder("rank", (player) -> {
            PlayerCache cache = PlayerCache.getCache(player);
            Rank rank = cache.getRank();

            return rank.getColor() + ChatColor.BOLD.toString() + rank.getName();
        });

My Plugin name is OrionFirstPlugin
i have essentialsx, essentialsxChat (what im using to show the placeholder), luckperms, protocolib, vault, and of course placeholderapi.