title: How to implement interface Serializable in scala?
body: <p>I have scala class like:</p>
  
  <pre><code>@Entity("users")
  class User(@Required val cid: String, val isAdmin: Boolean = false, @Required val dateJoined: Date = new Date() ) {
    @Id var id: ObjectId = _
  
  
  
      @Reference
    val foos = new ArrayList[Foo]
  
      }
  </code></pre>
  
  <p>If it was a Java class I would simply put implements java.io.Serializable but this does not work in scala. Also is foos as declared above is private or public?</p>