code: public Observable<String> beginGenerateVpnProfileAsync(String resourceGroupName, String virtualNetworkGatewayName, VpnClientParameters parameters) {
          return beginGenerateVpnProfileWithServiceResponseAsync(resourceGroupName, virtualNetworkGatewayName, parameters).map(new Func1<ServiceResponse<String>, String>() {
              @Override
              public String call(ServiceResponse<String> response) {
                  return response.body();
              }
          });
      }
docs: Generates VPN profile for P2S client of the virtual network gateway in the specified resource group. Used for IKEV2 and radius based authentication.
  
  @param resourceGroupName The name of the resource group.
  @param virtualNetworkGatewayName The name of the virtual network gateway.
  @param parameters Parameters supplied to the generate virtual network gateway VPN client package operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the String object