title: Filter/Query support in Elasticsearch Top hits Aggregation
body: <p>Elasticsearch documentation states that <code>The top_hits aggregation returns regular search hits, because of this many per hit features can be supported</code> Crucially, the list includes <code>Named filters and queries</code> </p>
  
  <p>But trying to add any filter or query throws <code>SearchParseException: Unknown key for a START_OBJECT</code></p>
  
  <p>Use case: I have items which have list of nested comments</p>
  
  <p>items{id} -> comments {date, rating}</p>
  
  <p>I want to get top rated comment for each item in the last week.</p>
  
  <pre><code>{
   "query": {
     "match_all": {}
    },
    "aggs": {
      "items": {
        "terms": {
          "field": "id",
          "size": 10
        },
        "aggs": {
          "comment": {
            "nested": {
              "path": "comments"
            },
            "aggs": {
              "top_comment": {
                "top_hits": {
                  "size": 1,
                  //need filter  here to select only comments of last week
                  "sort": {
                    "comments.rating": {
                      "order": "desc"
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
  </code></pre>
  
  <p>So is the documentation wrong, or is there any way to add a filter?</p>
  
  <p><a href="https://www.elastic.co/guide/en/elasticsearch/reference/2.1/search-aggregations-metrics-top-hits-aggregation.html" rel="nofollow">https://www.elastic.co/guide/en/elasticsearch/reference/2.1/search-aggregations-metrics-top-hits-aggregation.html</a>  </p>