code: @BetaApi
    public final ListDiskTypesPagedResponse listDiskTypes(ProjectZoneName zone) {
      ListDiskTypesHttpRequest request =
          ListDiskTypesHttpRequest.newBuilder()
              .setZone(zone == null ? null : zone.toString())
              .build();
      return listDiskTypes(request);
    }
docs: Retrieves a list of disk types available to the specified project.
  
  <p>Sample code:
  
  <pre><code>
  try (DiskTypeClient diskTypeClient = DiskTypeClient.create()) {
  ProjectZoneName zone = ProjectZoneName.of("[PROJECT]", "[ZONE]");
  for (DiskType element : diskTypeClient.listDiskTypes(zone).iterateAll()) {
  // doThingsWith(element);
  }
  }
  </code></pre>
  
  @param zone The name of the zone for this request.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails