String activityDefId = activityXml.getParticiSpecActID();
List<Participant> list = workItemService.queryActivityExecutors(processInstId, activityDefId);
if(list == null || list.isEmpty()) {
throw new ParticipantProcessEngineException("指定执行环节【" + activityDefId + "】必须已经执行完成");
}
return list;
}