title: Storing a list of enums in firebase
body: <p>I have the following code:</p>
  
  <pre><code>public class TestClass {
       public ArrayList&lt;ObjectTypes&gt; list = new ArrayList&lt;&gt;();
       public TestClass(){
          list.add(ObjectTypes.type1);
       }
  }
  
  public enum ObjectTypes {
     type1,
     type2,
     type3,
     type4,
  }
  
  fb.child("Test").setValue(new TestClass());
  </code></pre>
  
  <p>where fb is a DatabaseReference.</p>
  
  <p>When running the code the application crashes and the following error appears:</p>
  
  <blockquote>
    <p>com.google.firebase.database.DatabaseException: No properties to
    serialize found on class
    ObjectTypes</p>
  </blockquote>
  
  <p>This problem did not appear in the old Firebase.</p>