code: public Observable<ServiceResponse<ExpressRouteCircuitConnectionInner>> createOrUpdateWithServiceResponseAsync(String resourceGroupName, String circuitName, String peeringName, String connectionName, ExpressRouteCircuitConnectionInner expressRouteCircuitConnectionParameters) {
          if (resourceGroupName == null) {
              throw new IllegalArgumentException("Parameter resourceGroupName is required and cannot be null.");
          }
          if (circuitName == null) {
              throw new IllegalArgumentException("Parameter circuitName is required and cannot be null.");
          }
          if (peeringName == null) {
              throw new IllegalArgumentException("Parameter peeringName is required and cannot be null.");
          }
          if (connectionName == null) {
              throw new IllegalArgumentException("Parameter connectionName is required and cannot be null.");
          }
          if (this.client.subscriptionId() == null) {
              throw new IllegalArgumentException("Parameter this.client.subscriptionId() is required and cannot be null.");
          }
          if (expressRouteCircuitConnectionParameters == null) {
              throw new IllegalArgumentException("Parameter expressRouteCircuitConnectionParameters is required and cannot be null.");
          }
          Validator.validate(expressRouteCircuitConnectionParameters);
          final String apiVersion = "2018-08-01";
          Observable<Response<ResponseBody>> observable = service.createOrUpdate(resourceGroupName, circuitName, peeringName, connectionName, this.client.subscriptionId(), expressRouteCircuitConnectionParameters, apiVersion, this.client.acceptLanguage(), this.client.userAgent());
          return client.getAzureClient().getPutOrPatchResultAsync(observable, new TypeToken<ExpressRouteCircuitConnectionInner>() { }.getType());
      }
docs: Creates or updates a Express Route Circuit Connection in the specified express route circuits.
  
  @param resourceGroupName The name of the resource group.
  @param circuitName The name of the express route circuit.
  @param peeringName The name of the peering.
  @param connectionName The name of the express route circuit connection.
  @param expressRouteCircuitConnectionParameters Parameters supplied to the create or update express route circuit circuit connection operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable for the request