Coding when stacked armor is dropped, its picked up stacked

Hi Im trying to make a plugin so armor and tools are picked up stacked when they are dropped stacked. could anybody help me out here? My current code:

Code:

public class Main extends JavaPlugin implements Listener{
   
    public void onEnable() {
        getServer().getPluginManager().registerEvents(this, this);
      }
   
    @EventHandler
    public void onPlayerPickupArmour(PlayerPickupItemEvent e) {