src/PubSub/Manager.php
public function addSubscriberInterface(SubscriberInterface $interface)
    {
        $subscribers = $this->getInterfaceSubscribers($interface);
        foreach ($subscribers as $row) {
            $this->subscribe($row[0], $row[1], $row[2]);
        }
        return $subscribers;
    }
public function addSubscriberInterface(SubscriberInterface $interface)
    {
        $subscribers = $this->getInterfaceSubscribers($interface);
        foreach ($subscribers as $row) {
            $this->subscribe($row[0], $row[1], $row[2]);
        }
        return $subscribers;
    }
Subscribe to all of the event subscribers defined in passed obj

@param SubscriberInterface $interface object implementing subscriber interface

@return array a normalized list of subscriptions added.
each returned is array(eventName, callable, priority)