code: public SubnetInner createOrUpdate(String resourceGroupName, String virtualNetworkName, String subnetName, SubnetInner subnetParameters) {
          return createOrUpdateWithServiceResponseAsync(resourceGroupName, virtualNetworkName, subnetName, subnetParameters).toBlocking().last().body();
      }
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.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws CloudException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the SubnetInner object if successful.