我正在使用es 7.3.1和elasticsearch高级客户端7.3.1我们有一个由3个索引组成的别名。

Alias Name :  employee_search
Indexes in this alias : contract_employee,permanent_employee,client

我正在搜索这个别名

SearchRequest searchReq = new SearchRequest("employee_search");
WrapperQueryBuilder qb = QueryBuilders.wrapperQuery(searchQuery); //i am preparing a dsl query
SearchSourceBuilder sbb = new SearchSourceBuilder();
sbb.query(qb);
searchReq.source(sbb);
SearchResponse resp = esClient.search(searchReq, RequestOptions.DEFAULT);

作为回应，我需要一个聚合，在这里我可以得到索引方面的点击（哪个索引给出了多少次点击？）需要实现的聚合是

{
  "aggs": {
    "index_wise_count": {
      "terms": {
        "field": "_index"
      }
    }
  }
}

如何在现有的搜索响应中实现这一点？
我试过但没有成功：

SearchRequest searchReq = new SearchRequest("employee_search");
    WrapperQueryBuilder qb = QueryBuilders.wrapperQuery(searchQuery); //i am preparing a dsl query
    SearchSourceBuilder sbb = new SearchSourceBuilder();
    sbb.query(qb);
    sbb.aggreagation(AggregationBuilders.terms("index_wise_count").field("index"));
    searchReq.source(sbb);
    SearchResponse resp = esClient.search(searchReq, RequestOptions.DEFAULT);