code: @BetaApi
    public final Operation deleteDisk(ProjectZoneDiskName disk) {
  
      DeleteDiskHttpRequest request =
          DeleteDiskHttpRequest.newBuilder().setDisk(disk == null ? null : disk.toString()).build();
      return deleteDisk(request);
    }
docs: Deletes the specified persistent disk. Deleting a disk removes its data permanently and is
  irreversible. However, deleting a disk does not delete any snapshots previously made from the
  disk. You must separately delete snapshots.
  
  <p>Sample code:
  
  <pre><code>
  try (DiskClient diskClient = DiskClient.create()) {
  ProjectZoneDiskName disk = ProjectZoneDiskName.of("[PROJECT]", "[ZONE]", "[DISK]");
  Operation response = diskClient.deleteDisk(disk);
  }
  </code></pre>
  
  @param disk Name of the persistent disk to delete.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails