title: Add _timestamp to Elasticsearch results using Java API
body: <p>I have an Elasticsearch index which has <code>_timestamp</code> populated on every record. Using Marvel or curl I can get the <code>_timestamp</code> in the "fields" part of the result for example: </p>
  
  <pre><code>GET index/type/_search?fields=_timestamp,_source
  {
     "took": 11,
     "timed_out": false,
     "_shards": {
        "total": 3,
        "successful": 3,
        "failed": 0
     },
     "hits": {
        "total": 116888,
        "max_score": 1,
        "hits": [
           {
              "_index": "index",
              "_type": "type",
              "_id": "mXJdWqSLSfykbMtChiCRjA",
              "_score": 1,
              "_source": {
                 "results": "example",
              },
              "fields": {
                 "_timestamp": 1443618319514
              }
           },...
  </code></pre>
  
  <p>However when doing a search using the Java API I cant get it to return the <code>_timestamp</code>.</p>
  
  <pre><code>SearchRequestBuilder builder= client.prepareSearch(index)
              .addFacet(facet)
              .setFrom(start)
              .setSize(limit);
  SearchResponse response = builder.execute().actionGet();
  </code></pre>
  
  <p>Can anyone tell me how to ask for <code>_timestamp</code> too?</p>