code: public Observable<DataMigrationServiceInner> updateAsync(String groupName, String serviceName, DataMigrationServiceInner parameters) {
          return updateWithServiceResponseAsync(groupName, serviceName, parameters).map(new Func1<ServiceResponse<DataMigrationServiceInner>, DataMigrationServiceInner>() {
              @Override
              public DataMigrationServiceInner call(ServiceResponse<DataMigrationServiceInner> response) {
                  return response.body();
              }
          });
      }
docs: Create or update DMS Service Instance.
  The services resource is the top-level resource that represents the Data Migration Service. The PATCH method updates an existing service. This method can change the kind, SKU, and network of the service, but if tasks are currently running (i.e. the service is busy), this will fail with 400 Bad Request ("ServiceIsBusy").
  
  @param groupName Name of the resource group
  @param serviceName Name of the service
  @param parameters Information about the service
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable for the request