code: @BetaApi
    public final ListVpnTunnelsPagedResponse listVpnTunnels(ProjectRegionName region) {
      ListVpnTunnelsHttpRequest request =
          ListVpnTunnelsHttpRequest.newBuilder()
              .setRegion(region == null ? null : region.toString())
              .build();
      return listVpnTunnels(request);
    }
docs: Retrieves a list of VpnTunnel resources contained in the specified project and region.
  
  <p>Sample code:
  
  <pre><code>
  try (VpnTunnelClient vpnTunnelClient = VpnTunnelClient.create()) {
  ProjectRegionName region = ProjectRegionName.of("[PROJECT]", "[REGION]");
  for (VpnTunnel element : vpnTunnelClient.listVpnTunnels(region).iterateAll()) {
  // doThingsWith(element);
  }
  }
  </code></pre>
  
  @param region Name of the region for this request.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails