title: AWS Connect and Lex - Cannot reference Contact Attribute
body: <p>For reference, here is the flow in question:</p>
  
  <p>"Get Customer Input" (Lex) -> "Set Contact Attribute" -> "Play Prompt" </p>
  
  <p>After the call to Lex, I set a contact attribute using "Save Text As Attribute" option:</p>
  
  <p>DestinationKey                          Value
  ProductType                             $.Lex.SessionAttributes.ProductType</p>
  
  <p>Then, in the "Play Prompt" I can't reference the set attribute. I use "Text to speech (Ad hoc)" and have tried the following syntax:</p>
  
  <ul>
  <li>$.ProductType</li>
  <li>$.System.ProductType</li>
  <li>$.User.ProductType</li>
  <li>$.External.ProductType</li>
  </ul>
  
  <p>The interesting thing is, if I add a "Check contact attributes" after the "Set contact attributes" it does match on "User Defined" attribute "ProductType". </p>
  
  <p>How may I reference the attribute?</p>