pocketmine\event\entity\EntityRegainHealthEvent::getRegainReason PHP Method

    public function getRegainReason()
    {
        return $this->reason;
    }

 public function onEntityRegainHealth(EntityRegainHealthEvent $event)
 {
     switch ($event->getRegainReason()) {
         case EntityRegainHealthEvent::CAUSE_REGEN:
         case EntityRegainHealthEvent::CAUSE_EATING:
         case EntityRegainHealthEvent::CAUSE_CUSTOM:
             $event->setCancelled(true);
             break;
         case EntityRegainHealthEvent::CAUSE_MAGIC:
             // Do nothing
             break;
         default:
             $event->setCancelled(true);
             break;
     }
 }