code: public ServiceFuture<String> beginGeneratevpnclientpackageAsync(String resourceGroupName, String virtualNetworkGatewayName, VpnClientParameters parameters, final ServiceCallback<String> serviceCallback) {
          return ServiceFuture.fromResponse(beginGeneratevpnclientpackageWithServiceResponseAsync(resourceGroupName, virtualNetworkGatewayName, parameters), serviceCallback);
      }
docs: Generates VPN client package for P2S client of the virtual network gateway in the specified resource group.
  
  @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.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object