title: Received invalid response from Lambda: Can not construct instance of IntentResponse
body: <p>I have been trying out the lambda codehook on aws lex and this what the response that I'll be returning looks like</p>
  
  <pre><code>response = {
              "dialogAction" : {
                  "type": "ElicitSlot",
                  "message": {    
                      "contentType": "PlainText",
                      "content": "Please make enter value of slot1 first before proceeding."
                  },
                "intentName": "AWSLexIntentName",
                "slots": {
                      "slot1" : null,
                      "slot2" : null,
                      "slot3" : null,
                      "slot4" : null,
                      "slot5" : null
                },
                "slotToElicit" : "slot1"
              }
          }
  </code></pre>
  
  <p>I've already tried testing it using the lambda test events but when trying it out on Lex I keep getting the error </p>
  
  <pre><code>An error has occurred: Invalid Lambda Response: Received invalid response from Lambda: Can not construct instance of IntentResponse, problem: The validated object is null at [Source: {}; line: 1, column: 2]
  </code></pre>
  
  <p>I'm still new to amazon web services and don't have that much knowledge in programming all in all but I can't trace back this error since this is "Source" key isn't found in any of my code or the amazon documentation. Also thanks for taking your time reading this.</p>