title: Return type of spring data projection
body: <p>I am new to using Spring projections. So here's the problem I am having :
  These are my domain class, projection, controller, Test method :</p>
  
  <pre><code>public class S{
      private int id;
      private String name;
      private String state;
      ...
  }
  
  public interface sProjection{
      public int getId();
      public int getName();
  }
  
  repository method : 
  public List&lt;sProjection&gt; findByState(String state);
  
  controller :
  @GetMapping("/list")
  public List&lt;sProjection&gt; scopeList(){
      List&lt;sProjection&gt; sThumbNailList = findByState("Protected")
      return sThumbNailList;
  }
  
  Test method :
  @Test
  public void testGet(){
      ResponseEntity&lt;List&lt;sProjection&gt;&gt; responseEntity = this.restTemplate.exchange("/webapi/s/list", HttpMethod.GET, null,  new ParameterizedTypeReference&lt;List&lt;sProjection&gt;&gt;() {});
  }
  </code></pre>
  
  <p>The problem i am having is in the test method I am getting error saying since <code>sProjection</code> is an interface you can't instantiate it. Does anyone know what's the alternative to this ?
  I tried using <code>List&lt;Object&gt; list</code> instead but <code>list.get</code> gets me a LinkedHashMap instead of a Object which I can cast to (sProjection). Anyone faced this problem before and figured out solution ?</p>