title: Kryo serialization refuses to register class
body: <p>I'm trying to use kryo serialization with:    </p>
  
  <pre><code>kryo.setRegistrationRequired(true);
  </code></pre>
  
  <p>I keep getting the following error saying that a certain class is not registered:</p>
  
  <pre><code>java.lang.IllegalArgumentException: Class is not registered: com.my.package.MyClass[]
  Note: To register this class use: kryo.register(com.my.package.MyClass[].class);
  </code></pre>
  
  <p>However, I do register it:</p>
  
  <pre><code>kryo.register(classOf[MyClass[_]])
  </code></pre>
  
  <p>When I set Log.TRACE() I get the following output:</p>
  
  <pre><code>00:11 TRACE: [kryo] Register class ID 51: com.my.package.MyClass (com.esotericsoftware.kryo.serializers.FieldSerializer)
  </code></pre>
  
  <p>Why does it say it is not registered, when the trace logger prints that it has been registered. I cannot find any useful documentation on the matter. Has anyone experienced this before? If it helps i'm running Apache Spark v0.8.1</p>