purchases.subscriptions.get RESET API response returns 'developerPayload' key data null in android In-app purchase

Question

In-app purchase purchases.subscriptions.get RESET API response returns 'developerPayload' key data null sometimes,why I am getting null?

Following is url: https://androidpublisher.googleapis.com/androidpublisher/v3/applications/{packageName}/purchases/subscriptions/{subscriptionId}/tokens/{token}

Following is response:

{\n "startTimeMillis": "1644587777978",\n "expiryTimeMillis": "1644588195445",\n "autoRenewing": true,\n "priceCurrencyCode": "INR",\n "priceAmountMicros": "420000000",\n "countryCode": "IN",\n "developerPayload": "",\n "paymentState": 1,\n "orderId": "GPA.3305-3322-1924-71944",\n "purchaseType": 0,\n "acknowledgementState": 1,\n "kind": "androidpublisher#subscriptionPurchase"\n}