code: public Observable<String> getVpnProfilePackageUrlAsync(String resourceGroupName, String virtualNetworkGatewayName) {
          return getVpnProfilePackageUrlWithServiceResponseAsync(resourceGroupName, virtualNetworkGatewayName).map(new Func1<ServiceResponse<String>, String>() {
              @Override
              public String call(ServiceResponse<String> response) {
                  return response.body();
              }
          });
      }
docs: Gets pre-generated VPN profile for P2S client of the virtual network gateway in the specified resource group. The profile needs to be generated first using generateVpnProfile.
  
  @param resourceGroupName The name of the resource group.
  @param virtualNetworkGatewayName The name of the virtual network gateway.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable for the request