code: public Observable<List<ExpressionRootInner>> listExpressionTracesAsync(String resourceGroupName, String workflowName, String runName, String actionName, String repetitionName) {
          return listExpressionTracesWithServiceResponseAsync(resourceGroupName, workflowName, runName, actionName, repetitionName).map(new Func1<ServiceResponse<List<ExpressionRootInner>>, List<ExpressionRootInner>>() {
              @Override
              public List<ExpressionRootInner> call(ServiceResponse<List<ExpressionRootInner>> response) {
                  return response.body();
              }
          });
      }
docs: Lists a workflow run expression trace.
  
  @param resourceGroupName The resource group name.
  @param workflowName The workflow name.
  @param runName The workflow run name.
  @param actionName The workflow action name.
  @param repetitionName The workflow repetition.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the List&lt;ExpressionRootInner&gt; object