code: public ServiceFuture<WorkflowInner> getByResourceGroupAsync(String resourceGroupName, String workflowName, final ServiceCallback<WorkflowInner> serviceCallback) {
          return ServiceFuture.fromResponse(getByResourceGroupWithServiceResponseAsync(resourceGroupName, workflowName), serviceCallback);
      }
docs: Gets a workflow.
  
  @param resourceGroupName The resource group name.
  @param workflowName The workflow name.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object