public ArrayList<String> stampfer = new ArrayList<String>();

    @EventHandler
    public void onDamage(EntityDamageEvent e) {
        if(e.getEntity() instanceof Player) {
            Player p = (Player) e.getEntity();
            if(stampfer.contains(p.getName())) {
                if(e.getCause() == DamageCause.FALL) {

                    double damage = e.getDamage();
                    for(Entity all : p.getNearbyEntities(4, 4, 4)) {
                        if(all instanceof Player) {
                            Player target = (Player) all;
                            target.damage(damage);
                        }
                    }
                    if(damage >= 4.0) {
                        damage = 4.0;
                    }

                    e.setDamage(damage);
                }
            }
        }
    }

    @EventHandler
    public void onJoin(PlayerJoinEvent e) {
        stampfer.add(e.getPlayer().getName());
    }