title: Objectify Projection Query with Filters
body: <p>Given the class</p>
  
  <pre><code>@Entity
  public class Goat{
     Long pen;
     Long car;
     Boolean active;
     …
  }
  </code></pre>
  
  <p>I need to create a projection query that returns a list of <code>Long</code>s. How should I edit the following so it works?</p>
  
  <pre><code>List&lt;Long&gt; cars = ofy().load().type(Goat.class).filter("pen", pen).filter("active", true).project("car").list();
  </code></pre>