Shopify Integration as Payment Partner - Null parameters in requests from shopify

[jazzcash]

I am integrating my payment gateway with Shopify, as payment partner. The problem is that I am receiving some null values in mandatory parameters from Shopify. Below are the 2 sample requests, along with the snapshot of shopify documentation. I would appreciate if anyone has the idea whats wrong here. I am unable to perform unit tests with Shopify.

Start Session Request:

{
  "id": "<unique identifier>",
  "gid": "gid://shopify/PaymentSession/<unique identifier>",
  "group": "<group>",
  "amount": "869.94",
  "currency": "PKR",
  "test": true,
  "merchant_locale": null,
  "payment_method": null,
  "proposed_at": "0001-01-01T00:00:00",
  "customer": {
    "billing_address": null,
    "shipping_address": null,
    "email": "<email>",
    "phone_number": null,
    "locale": "en-PK"
  },
  "kind": "sale"
}

Refund Request:

{
  "id": "<unique identifier>",
  "gid": "gid://shopify/RefundSession/<unique identifier>",
  "payment_id": null,
  "amount": "730.74",
  "currency": "PKR",
  "test": false,
  "merchant_locale": null,
  "proposed_at": "0001-01-01T00:00:00"
}