title: Scala 2.9.1 issue? => MappingException: Setting property bitmap$init$0 to null
body: <p>I use scala 2.9.1, Play Framework 2.0.4, Spring 3.2.0, Spring Data 2.1.0 and neo4j 1.8.</p>
  
  <p>I've got this model object:</p>
  
  <pre><code>package models
  
  import java.lang.{String, Long}
  import org.springframework.data.neo4j.annotation.{Indexed, NodeEntity, GraphId}
  
      @NodeEntity
      class Article(_title: String) {
  
        @GraphId var id: Long = _     //causes the error !!
  
        @Indexed val title: String = _title
  
        def this() {
          this("no title")
        }
  
        override def hashCode(): Int = {
          41 * title.hashCode
        }
  
        override def equals(other: Any): Boolean = {
          other match {
            case that: Article =&gt; (that canEqual this) &amp;&amp; ((this.id == that.id) &amp;&amp; (this.title == that.title))
            case _ =&gt; false
          }
        }
  
        def canEqual(other: Any) = other.isInstanceOf[Article]
      }
  </code></pre>
  
  <p>Before, I used Scala 2.10 with Play Framework 2.1-RC2 and the same version of Spring Data, nothing bad happened and I never touched the code since (it's a personal project).</p>
  
  <p>I've got this error:</p>
  
  <pre><code>MappingException: Setting property `bitmap$init$0` to null on models.Article@466b9021
  </code></pre>
  
  <p>I found this similar <a href="https://stackoverflow.com/questions/10760970/scala-hibernate-jpa-ignore-autogenerated-bitmapinit0-mapping/13327497#13327497">post</a> explaining (especially in the comments) that it seems that anterior scala version to 2.10.0 causes the issue.</p>
  
  <p>Has anyone come across this issue? How could I fix it?</p>