title: Do valueTransformer in kafka stream can have access to tombstone?
body: <p>is it possible to have access to the tombstone that an upstream Ktable process ?</p>
  <p>Let say I would like to apply a logic to every deletion that happen to an upstream KTable, that is, do ValueTransformer get forwarded delete Event ?</p>
  <p><code>kTable.transform(delete Event)</code></p>
  <p>if not, is there another way to achieve this ?</p>