title: Deleting all the associate persistent disks when deleting cluster
body: <p>According to the documentation when deleting a cluster the persistent disk will still exist(<a href="https://cloud.google.com/kubernetes-engine/docs/how-to/deleting-a-cluster" rel="nofollow noreferrer">https://cloud.google.com/kubernetes-engine/docs/how-to/deleting-a-cluster</a>).  I wanna delete all the associate persistent disks when deleting cluster but I don't know the name/id of persistent disk. 
  Cluster get API doesn't have any information about the disks and nodes.</p>
  
  <p><code>resp, err := containerService.Projects.Zones.Clusters.Get(project, zone, cluster).Context(ctx).Do()
  </code></p>