title: Sink must be binary when source is binary dataset
body: <p>I am new to the Azure Data Factory scene, trying out the copy data tutorial where I have an InputDataset with emp.txt with the following information:</p>
  
  <pre><code>firstname, lastname
  John, Doe
  Jane, Doe
  </code></pre>
  
  <p>And I want to have an OutputDataset in json format.</p>
  
  <pre><code>{
   "firstname" : John,
   "lastname" : Doe
  }
  </code></pre>
  
  <p>How can I set it up correctly in the Pipeline? It keeps telling me sink must be binary when source is binary dataset.</p>