title: Fail to load PiplineModel/LogisticRegressionModel mlib spark
body: <p>I have a problem with loading a serialized <code>PiplineModel</code> that contains a <code>LogisticRegressionModel</code> stage. I get:</p>
  
  <pre><code>java.lang.IllegalArgumentException: Field "coefficients" does not exist.
  </code></pre>
  
  <p>I had tried both loading the full pipeline and just logistic stage and get the same error. Additionally, I checked whether <code>coeficients()</code> returns values prior to saving the model and it does.</p>
  
  <p>Any ideas of what might be happening? </p>