Example
You can cancel a fall damage by using the EntityDamageEvent
@EventHandler
public void onEntityDamage(EntityDamageEvent e) {
Entity tookDamage = e.getEntity();
DamageCause cause = e.getCause();
if (cause == DamageCause.FALL){
//Damage was caused by falling, cancel it
e.setCancelled(true);
}
