title: NEST returns null instead of fields
body: <p>I'm working with elastic for a long time, but I have never written a code that fetches some data. And now I'm in trouble.</p>
  
  <p>I have an index where I want to retrieve some documents projected on some field. I could literally write it in SQL</p>
  
  <pre class="lang-sql prettyprint-override"><code>SELECT myDocumentField
  FROM myIndex
  </code></pre>
  
  <p>But for some reason I'm getting nulls instead of values.</p>
  
  <p>I have 6 documents in my index. So I write following query:</p>
  
  <pre><code>var elasticServiceNumbers = await _elasticClient.SearchAsync&lt;ElasticRequest&gt;(
                                  s =&gt; s.Query(Selector));
  </code></pre>
  
  <p>It works as expected and return these 6 values, except that all their fields are nulls</p>
  
  <p><a href="https://i.stack.imgur.com/R2uy5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/R2uy5.png" alt="enter image description here"></a></p>
  
  <p>Okay, I'm trying to add fields as well:</p>
  
  <pre><code>var elasticServiceNumbers = await _elasticClient.SearchAsync&lt;ElasticRequest&gt;(
                                  s =&gt; s.StoredFields(sf =&gt; sf.Fields(f =&gt; f.ServiceNumber))
                                        .Query(Selector));
  var elasticServiceNumbers2 = await _elasticClient.SearchAsync&lt;ElasticRequest&gt;(
                                  s =&gt; s.Source(sf =&gt; sf.Includes(fds =&gt; fds.Field(f =&gt; f.ServiceNumber)))
                                        .Query(Selector));
  </code></pre>
  
  <p>But still out of luck, and fields keep their null values. </p>
  
  <p>Kibana shows that this fields exist on the index:</p>
  
  <p><a href="https://i.stack.imgur.com/KfnUN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KfnUN.png" alt="enter image description here"></a></p>
  
  <p>What could be wrong here?</p>
  
  <hr>
  
  <p>Kibana query</p>
  
  <pre><code>{
    "version": true,
    "size": 500,
    "sort": [
      {
        "_score": {
          "order": "desc"
        }
      }
    ],
    "_source": {
      "excludes": []
    },
    "aggs": {
      "2": {
        "date_histogram": {
          "field": "@timestamp",
          "interval": "3h",
          "time_zone": "Asia/Baghdad",
          "min_doc_count": 1
        }
      }
    },
    "stored_fields": [
      "*"
    ],
    "script_fields": {},
    "docvalue_fields": [
      "@timestamp",
      "fields.Date",
      "fields.DeserializedMessage.Message.Date",
      "fields.DeserializedMessage.Message.Periods.Begin",
      "fields.DeserializedMessage.Message.Periods.End",
      "fields.DeserializedMessage.Message.ResponseDate",
      "fields.Periods.Begin",
      "fields.Periods.End",
      "fields.ResponseDate"
    ],
    "query": {
      "bool": {
        "must": [
          {
            "match_all": {}
          },
          {
            "range": {
              "@timestamp": {
                "gte": 1527973200000,
                "lte": 1528577999999,
                "format": "epoch_millis"
              }
            }
          }
        ],
        "filter": [],
        "should": [],
        "must_not": []
      }
    },
    "highlight": {
      "pre_tags": [
        "@kibana-highlighted-field@"
      ],
      "post_tags": [
        "@/kibana-highlighted-field@"
      ],
      "fields": {
        "*": {}
      },
      "fragment_size": 2147483647
    }
  }
  </code></pre>