// +optional
  optional int64 generation = 7;

  // CreationTimestamp is a timestamp representing the server time when this object was
  // created. It is not guaranteed to be set in happens-before order across separate operations.
  // Clients may not set this value. It is represented in RFC3339 form and is in UTC.
  //
  // Populated by the system.
  // Read-only.
  // Null for lists.