<?php

namespace Autogedal\AutogedalHelper\Observer;

use Magento\Framework\Event\ObserverInterface;

class ProductWarranty implements ObserverInterface
{
    public function __construct()
    {
        // Observer initialization code...
        // You can use dependency injection to get any class this observer may need.
    }

    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        $productObj = $observer->getEvent()->getProduct();
        $productObj->setWarranty(5);
    }
}