// +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.ObjectMeta metadata = 1;

  // spec defines the desired characteristics of a volume requested by a pod author.
  // More info: https://kubernetes.io/docs/concepts/storage/persistent-volumes#persistentvolumeclaims
  // +optional
  optional PersistentVolumeClaimSpec spec = 2;