spigot kill entity

1@EventHandler
2	public void onEntitySpawn(EntitySpawnEvent event) {
3		if (event.getEntityType() == EntityType.CREEPER) {
4			if (event.getEntity() instanceof Damageable) {
5				
6				Damageable creeper = (Damageable) event.getEntity();
7				creeper.damage(1000);
8			}
9		}
10    }