code: public Observable<ExpressRouteConnectionInner> beginCreateOrUpdateAsync(String resourceGroupName, String expressRouteGatewayName, String connectionName, ExpressRouteConnectionInner putExpressRouteConnectionParameters) {
          return beginCreateOrUpdateWithServiceResponseAsync(resourceGroupName, expressRouteGatewayName, connectionName, putExpressRouteConnectionParameters).map(new Func1<ServiceResponse<ExpressRouteConnectionInner>, ExpressRouteConnectionInner>() {
              @Override
              public ExpressRouteConnectionInner call(ServiceResponse<ExpressRouteConnectionInner> response) {
                  return response.body();
              }
          });
      }
docs: Creates a connection between an ExpressRoute gateway and an ExpressRoute circuit.
  
  @param resourceGroupName The name of the resource group.
  @param expressRouteGatewayName The name of the ExpressRoute gateway.
  @param connectionName The name of the connection subresource.
  @param putExpressRouteConnectionParameters Parameters required in an ExpressRouteConnection PUT operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the ExpressRouteConnectionInner object