code: public Observable<VirtualWANInner> getByResourceGroupAsync(String resourceGroupName, String virtualWANName) {
          return getByResourceGroupWithServiceResponseAsync(resourceGroupName, virtualWANName).map(new Func1<ServiceResponse<VirtualWANInner>, VirtualWANInner>() {
              @Override
              public VirtualWANInner call(ServiceResponse<VirtualWANInner> response) {
                  return response.body();
              }
          });
      }
docs: Retrieves the details of a VirtualWAN.
  
  @param resourceGroupName The resource group name of the VirtualWan.
  @param virtualWANName The name of the VirtualWAN being retrieved.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the VirtualWANInner object