It contains the Signal object.
Inheritance: extends Symfony\Component\EventDispatcher\Event
 /**
  * @covers eZ\Publish\Core\MVC\Symfony\Event\SignalEvent::__construct
  * @covers eZ\Publish\Core\MVC\Symfony\Event\SignalEvent::getSignal
  */
 public function testGetSignal()
 {
     $signal = $this->getMock('eZ\\Publish\\Core\\SignalSlot\\Signal');
     $event = new SignalEvent($signal);
     $this->assertSame($signal, $event->getSignal());
 }