src/EventManager/EventManager.php
public function trigger($eventName, $target = null, $argv = [])
    {
        $event = $eventName instanceof EventInterface
            ? $eventName
            : $this->getEvent($eventName, $target, $argv);

        return $this->triggerListeners($event);
    }
public function trigger($eventName, $target = null, $argv = [])
    {
        $event = $eventName instanceof EventInterface
            ? $eventName
            : $this->getEvent($eventName, $target, $argv);

        return $this->triggerListeners($event);
    }
Trigger an event.

If no event instance is passed, it creates one prior to triggering.

@param EventInterface|string $eventName
@param object|string|null $target
@param array $argv

@return \Zend\EventManager\ResponseCollection