title: Elasticsearch returns empty json-objects
body: <p>I'm just getting started with elasticsearch with spring which is both technologies which are completely new to me. I have uploaded data to an elasticseach index with logstash and I can search it successfully using kebana. However when I try to return from an index to a webpage using spring it only returns empty json-objects, but the right amount of empty objects. Did I upload the data incorrectly or is something wrong with my code? I don't understand why this is happening and would appreciate any help I can get. You can find some code below.</p>
  <p>Code for type:</p>
  <pre><code>@Document(indexName=&quot;usmgbg_index&quot;, type=&quot;usmgbg_type&quot;)
  public class Usmgbg {
  
      @Id
      private String ID;
      private String Source, Name, Profession, Country, FileName, LastModified, OwnerID;
  }
  </code></pre>
  <p>Repository:</p>
  <pre><code>@Repository 
  public interface UsmgbgRepository extends ElasticsearchRepository&lt;Usmgbg, String&gt;{}
  </code></pre>
  <p>Controller:</p>
  <pre><code>@RestController
  public class UsmgbgController {
      @Autowired
      private UsmgbgRepository repository;
      
      @GetMapping(&quot;usmgbg/findall&quot;)
      public List&lt;Usmgbg&gt; findAllCustomers() {
  
          List&lt;Usmgbg&gt; items = new ArrayList&lt;&gt;();
          repository.findAll().forEach(items::add);
        
          return items;
      } 
  }
  </code></pre>
  <p>The output I'm getting from findAllCustomers looks like:</p>
  <pre><code>[{},{},{},{},....]
  </code></pre>