src/Application/SimpleApplication.php
public function eventstream(EventStreamInterface $eventstream = null) : EventStreamInterface
    {
        if ($eventstream){
            $this->eventstream = $eventstream;
        }
        if (!$this->eventstream){
            $this->eventstream = new NullEventStream;
        }
        return $this->eventstream;
    }
public function eventstream(EventStreamInterface $eventstream = null) : EventStreamInterface
    {
        if ($eventstream){
            $this->eventstream = $eventstream;
        }
        if (!$this->eventstream){
            $this->eventstream = new NullEventStream;
        }
        return $this->eventstream;
    }
Set/get event stream

@param EventStreamInterface $eventstream

@return EventStreamInterface