HashMap<Player,Player> playerh = new HashMap<>();
      @SuppressWarnings("deprecation")
	@EventHandler
      public void onDamage(EntityDamageByEntityEvent e) {
    	 if (e.getDamager() instanceof Player) {
    		 Player player = (Player) e.getDamager();
    		 LivingEntity entity = (LivingEntity) e.getEntity();
    		 double health = entity.getHealth() - e.getDamage();
    		 double maxhealth = entity.getMaxHealth();
    		 int inthealth = (int) health;
    		 int intmaxhealth = (int) maxhealth;
    		 BossBar bar = Bukkit.createBossBar(ChatColor.LIGHT_PURPLE + "Damaged Entity's Hp: " + ChatColor.RED + inthealth +  "♥ / " + intmaxhealth + "♥"  , BarColor.RED, BarStyle.SOLID);
             if (playerh.isEmpty()) {
            	 player.sendMessage("1");
            	 bar.setProgress(health/maxhealth);
            	 bar.addPlayer(player);
            	 playerh.put(player, player);
             } else {
            	 playerh.clear();
            	 bar.setProgress(health/maxhealth);
             }

             Bukkit.getScheduler().scheduleAsyncDelayedTask(this,() -> {
            	 bar.removePlayer(player);
            	 if (!playerh.isEmpty()) {
            	 playerh.clear();
            	 }
             }, 40);
    	 }
      }
}