title: kryo Encountered unregistered class ID, even though I've registered all classes
body: <p>I have a spark job that serializes an object with setRegistrationRequired(true).<br>
  I have added registrations for all the classes.<br>
  I have java code that deserializes the serialized object, also with setRegistrationRequired(true) and all appropriate registrations, making sure that the order of registrations is the same.  </p>
  
  <p>While deserializing, I get <code>com.esotericsoftware.kryo.KryoException: Encountered unregistered class ID: 113</code></p>
  
  <p>At first, I thought I was missing some class, but then realized if that was the case, I wouldn't be able to serialize the object in the first place, since <code>requiredRegistration</code> is set to <code>true</code>.</p>
  
  <p>so I'm not sure what I'm doing wrong here.</p>