聚合去重统计数量，使用transportClient api 执行失败

如下查询使用java transportClient api （java api 版本5.6）执行失败,  提示：{ "error" : "JsonGenerationException[Can not write a field name, expecting a value]"}
 "aggs": {
      "distict_count": {
          "cardinality": {
            "field": "id"   //id是long类型
          }
        }
    }
 
 
对应api：
CardinalityAggregationBuilder aggregation = AggregationBuilders.cardinality("distict_count") .field(CompoundConstants.COMPOUND_ID_NAME_PMS); searchRequestBuilder.addAggregation(aggregation);
 
怎么解决呢？