code: public Observable<NetworkInterfaceInner> getByResourceGroupAsync(String resourceGroupName, String networkInterfaceName) {
          return getByResourceGroupWithServiceResponseAsync(resourceGroupName, networkInterfaceName).map(new Func1<ServiceResponse<NetworkInterfaceInner>, NetworkInterfaceInner>() {
              @Override
              public NetworkInterfaceInner call(ServiceResponse<NetworkInterfaceInner> response) {
                  return response.body();
              }
          });
      }
docs: Gets information about the specified network interface.
  
  @param resourceGroupName The name of the resource group.
  @param networkInterfaceName The name of the network interface.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the NetworkInterfaceInner object