code: public void retryLastFailedTask(String workflowId) {
          Preconditions.checkArgument(StringUtils.isNotBlank(workflowId), "workflow id cannot be blank");
          stub.retryWorkflow(WorkflowServicePb.RetryWorkflowRequest.newBuilder()
                  .setWorkflowId(workflowId)
                  .build()
          );
      }
docs: Retries the last failed task in a workflow
  
  @param workflowId the workflow id of the workflow with the failed task