code: public ServiceFuture<SubnetInner> beginCreateOrUpdateAsync(String resourceGroupName, String virtualNetworkName, String subnetName, SubnetInner subnetParameters, final ServiceCallback<SubnetInner> serviceCallback) {
          return ServiceFuture.fromResponse(beginCreateOrUpdateWithServiceResponseAsync(resourceGroupName, virtualNetworkName, subnetName, subnetParameters), serviceCallback);
      }
docs: Creates or updates a subnet in the specified virtual network.
  
  @param resourceGroupName The name of the resource group.
  @param virtualNetworkName The name of the virtual network.
  @param subnetName The name of the subnet.
  @param subnetParameters Parameters supplied to the create or update subnet 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