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