Sulu\Bundle\MediaBundle\Entity\CollectionType::getId PHP Method

    public function getId()
    {
        return $this->id;
    }

 public function testPutSystemCollection()
 {
     $collection = $this->createCollection($this->collectionType2, ['en' => 'Test'], null, 'system_collections');
     $this->em->flush();
     $client = $this->createAuthenticatedClient();
     $client->request('PUT', '/api/collections/' . $collection->getId(), ['locale' => 'en-gb', 'type' => ['id' => $this->collectionType1->getId()], 'title' => 'Test Collection 2', 'description' => 'This Description 2 is only for testing']);
     $this->assertEquals(403, $client->getResponse()->getStatusCode());
 }