title: elasticsearch "fields" parameter with dot notation
body: <p>Elasticsearch's search API supports a "fields" parameter to limit the fields returned from the hits. It supports dot notation for sub-properties of a document as well. For example, a query</p>
  
  <pre><code>{
      "fields" : ["user.lastname"],
      "query" : {
          "term" : { "_id" : 1 }
      }
  }
  </code></pre>
  
  <p>will return hits as:</p>
  
  <pre><code>{
     "hits": [
          {"_id": 1,
           "user.lastname": "Smith"}
    ]
  }
  </code></pre>
  
  <p>I am wondering if there is an option to make it return as this instead:</p>
  
  <pre><code>{
     "hits": [
          {"_id": 1,
           "user": {"lastname": "Smith"}}
    ]
  }
  </code></pre>
  
  <p>The benefit of the second one is maintaining the same structure as the full document, as that the following data access logic is consistent.</p>