TaskService taskService = env.get(TaskService.class);

TaskImpl currentTask = (TaskImpl)taskService.getTask(taskId);

ExecutionImpl exec = currentTask.getProcessInstance();

//获取当前任务的活动节点
ActivityImpl currentActivity = exec.getActivity();

//获取该活动节点的IncomingTransition
TransitionImpl incomingTransition = (TransitionImpl)currentActivity.getIncomingTransitions().get(0);

//获取IncomingTransition的源活动节点
ActivityImpl sourceActivity = incomingTransition.getSource();

TransitionImpl backTransition = currentActivity.createOutgoingTransition();

//当前活动节点为新的回退Transition的源，而原来的“源”活动节点变成了目标活动节点
backTransition.setSource(currentActivity);
backTransition.setDestination(sourceActivity);
backTransition.setName("regect "+incomingTransition.getName());
taskService.completeTask(taskId,backTransition.getName());
return sourceActivity.getName();

}