Customer/EventListener/CustomerGroupListener.php
public function onUpdate(ResourceEventInterface $event)
    {
        $address = $this->getCustomerGroupFromEvent($event);

        $this->fixDefault($address);
    }
public function onUpdate(ResourceEventInterface $event)
    {
        $address = $this->getCustomerGroupFromEvent($event);

        $this->fixDefault($address);
    }
Update event handler.

@param ResourceEventInterface $event