code: public Observable<String> vpnDeviceConfigurationScriptAsync(String resourceGroupName, String virtualNetworkGatewayConnectionName, VpnDeviceScriptParameters parameters) {
          return vpnDeviceConfigurationScriptWithServiceResponseAsync(resourceGroupName, virtualNetworkGatewayConnectionName, parameters).map(new Func1<ServiceResponse<String>, String>() {
              @Override
              public String call(ServiceResponse<String> response) {
                  return response.body();
              }
          });
      }
docs: Gets a xml format representation for vpn device configuration script.
  
  @param resourceGroupName The name of the resource group.
  @param virtualNetworkGatewayConnectionName The name of the virtual network gateway connection for which the configuration script is generated.
  @param parameters Parameters supplied to the generate vpn device script operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the String object