How to create a click listener for Hangouts API in Dialogflow using webhook

Question

I am creating a chatbot using Dialogflow with Hangouts API with fulfillment. While specifying a button on Hangouts custom payload in Dialogflow (or in my webhook if required) that then triggers a another intent. My end goal is replicate the Quick Replies functionality of Facebook in Hangouts.

{
 "hangouts": {
"header": {},
"sections": [
  {
    "widgets": [

      {
        "buttons": [
         {
            "textButton": {
                "text": "Trigger another intent",
                  "onClick": {
                     "followupEventInput": {
                        "name": "event-name"
                     }
                   }
              }
           }
         ]
       }

     ]
   }
  ]
 }
}