mongodb使用group查询报错no such command: 'group'

        BasicDBObject key = new BasicDBObject();
        key.put("areaCode", 1);

        //条件
        BasicDBObject cond = new BasicDBObject();
        //初始化
        BasicDBObject initial = new BasicDBObject();
        initial.append("total", 0);
        //reduce
        String reduce = "function Reduce(doc, out) { " +
                "  out.total+=doc.caseKey;" +
                "}";
        BasicDBList groupList = (BasicDBList) mongoTemplate.getCollection(collectionName).group(key, cond, initial, reduce);
        if (groupList != null && groupList.size() > 0) {
            System.out.println("areaCode  total");
            for (int i = 0; i < groupList.size(); i++) {
                BasicDBObject obj = (BasicDBObject) groupList.get(i);
                System.out.println(obj.get("areaCode") + "" + obj.get("total"));
            }
        }

遇到了同样的问题，在CSDN看到了，希望阿里云团队能够给出正确、标准的答案~请查看