How to send custom Payload from Dialogflow fulfilment

I am trying to send custom payload from the webhook (Firebase Cloud Function) but I am not able to achieve what I am trying. In response I wanna get something like:

"fulfillmentMessages": [
    {
      "text": {
        "text": [
          "First question."
        ]
      }
    },
    {
      "text": {
        "text": [
          "What is your name?"
        ]
      }
    },
    "payload": {
      "deplay": "13 seconds"
    }
  ]

But right now I don’t know how to add Payload in the fulfillmentMessages Array. My current code is:

let response = ['First question.', 'What is your name?'];
agent.add(response);

I have tried this

agent.add(new Payload('PLATFORM_UNSPECIFIED', JSON.stringify(json)));

But then it does not send fulfillmentMessages array. Any solution?

[s22su]

In package.json: "dialogflow-fulfillment": "^0.5.0" —> "dialogflow-fulfillment": "^0.6.1"

Thanks @HSpens works as expected after update. Just for others who Google the same thing, the code to send custom payload is:

// const { Payload } = require("dialogflow-fulfillment");

const payload = {
  key: 'value',
  key2: 2
};

agent.add(
  new Payload(agent.UNSPECIFIED, payload, {rawPayload: true, sendAsMessage: true})
);

[ParticleDuality]

In package.json: "dialogflow-fulfillment": "^0.5.0" —> "dialogflow-fulfillment": "^0.6.1"

Thanks @HSpens works as expected after update. Just for others who Google the same thing, the code to send custom payload is:

// const { Payload } = require("dialogflow-fulfillment");

const payload = {
  key: 'value',
  key2: 2
};

agent.add(
  new Payload(agent.UNSPECIFIED, payload, {rawPayload: true, sendAsMessage: true})
);

God, man I was trying so hard to find a solution and this code resolved my issue. Thanks.