activiti 任务授权，把流程中当前任务授权个其他用户代为办理

/**
* 授权代办
* @param serDoc
/
@Transactional(readOnly = false)
public void authAgent(SerDoc serDoc) {
String agentUserLoginName=UserUtils.get(serDoc.getAgentUserId()).getLoginName();
String taskId=serDoc.getAct().getTaskId();
String ownerAssignee=actTaskService.getTask(taskId).getAssignee();
actTaskService.getProcessEngine().getTaskService().setOwner(taskId, ownerAssignee);
actTaskService.getProcessEngine().getTaskService().setAssignee(taskId, agentUserLoginName);
System.out.println("************"+actTaskService.getTask(taskId).getAssignee());
}