public void retryLastFailedTask(String workflowId) {
        Validate.notBlank(workflowId, "workflow id cannot be blank");
        postForEntityWithUriVariablesOnly("workflow/{workflowId}/retry", workflowId);
    }
Retries the last failed task in a workflow

@param workflowId the workflow id of the workflow with the failed task
client/src/main/java/com/netflix/conductor/client/http/WorkflowClient.java