code: public Observable<ExpressRouteConnectionListInner> listAsync(String resourceGroupName, String expressRouteGatewayName) {
          return listWithServiceResponseAsync(resourceGroupName, expressRouteGatewayName).map(new Func1<ServiceResponse<ExpressRouteConnectionListInner>, ExpressRouteConnectionListInner>() {
              @Override
              public ExpressRouteConnectionListInner call(ServiceResponse<ExpressRouteConnectionListInner> response) {
                  return response.body();
              }
          });
      }
docs: Lists ExpressRouteConnections.
  
  @param resourceGroupName The name of the resource group.
  @param expressRouteGatewayName The name of the ExpressRoute gateway.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the ExpressRouteConnectionListInner object