Example code

public void onEntityDamageByEntity(EntityDamageByEntityEvent e) {
        //Checks if the damager is a bullet and then returns the name of the player who fired it
        
	BulletHandler bHandler = new BulletHandler();
	String owner = bHandler.getBulletOwner(e.getDamager().getUniqueId().toString());
        if(owner == null) return;
	
	//Do stuff...
}

Example two

public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
	if(sender instanceof Player) {
		Player p = (Player) sender;
		if(args.length == 1) {
			if(args[0].equalsIgnoreCase("test")) {
				if(p.hasPermission("flansapi.test")) {
					VehicleHandler vHandler = new VehicleHandler();
					
					//The player is standing on a chest thus these coordinates are of the chest
					int cx = p.getLocation().getBlock().getX(),
					cy = p.getLocation().getBlock().getY(),
					cz = p.getLocation().getBlock().getZ();
					
					vHandler.spawnVehicle(p.getLocation().getWorld().getName(), cx, cy, cz, "vehicle", (cx+15), (cy+10), cz);
					p.sendMessage("§6You successfully spawned a vehicle!");
				}
			}
		} 
	} 
	return false;
}