tophits的Elasticsearch子聚合JAVA API不工作

import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.aggregations.AggregationBuilders;
import org.elasticsearch.search.aggregations.Aggregations;
import org.elasticsearch.search.aggregations.bucket.terms.Terms;
import org.elasticsearch.search.aggregations.metrics.tophits.TopHits;

public class ElasticsearchTopHitsExample {
    public static void main(String[] args) {
        try (RestHighLevelClient client = new RestHighLevelClient(RestClient.builder("localhost:9200"))) {
            SearchRequest request = new SearchRequest("your_index");
            request.source()
                    .query(QueryBuilders.matchAllQuery())
                    .size(0)
                    .aggregation(AggregationBuilders.terms("category_agg").field("category")
                            .subAggregation(AggregationBuilders.topHits("top_hits_agg")
                                    .size(5) // 设置返回的文档数量
                                    .sort("popularity", SortOrder.DESC) // 根据字段进行排序
                            )
                    );

            SearchResponse response = client.search(request, RequestOptions.DEFAULT);

            Aggregations aggregations = response.getAggregations();
            Terms categoryAgg = aggregations.get("category_agg");
            for (Terms.Bucket bucket : categoryAgg.getBuckets()) {
                String category = bucket.getKeyAsString();
                TopHits topHits = bucket.getAggregations().get("top_hits_agg");
                // 处理top hits聚合的结果
                // ...
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}