title: Tensorflow._api.v2.train has no attribute 'AdamOptimizer'
body: <p>When using </p>
  
  <pre><code>model.compile(optimizer = tf.train.AdamOptimizer(),
                loss = 'sparse_categorical_crossentropy',
                metrics=['accuracy'])
  </code></pre>
  
  <p>in my Jupyter Notebook the following Error pops up:</p>
  
  <p><strong>module 'tensorflow._api.v2.train' has no attribute 'AdamOptimizer'</strong></p>
  
  <p>Tensorflow Version: <strong>2.0.0-alpha0</strong></p>
  
  <hr>
  
  <p>Do you think the only possibility is to downgrade the TF version?</p>