Getting Truncated JSON response when calling UPS API using google app script - api

Question

I am using google app script to Call UPS api and generate shipping label. However the API response is truncated and i am unable to decode base64 encoded image which is part of the JSON response object as it is truncated.
I am also not getting any truncation error messages or responses from the UPS servers, neither is google apps script throwing an error
Have contacted UPS support with the JSON request and it seems to works fine at their end.
// Here is the code for API call.
function getLabel() {
var userName = "myUPS_username";
var password = "*********";
var accessKey = "my_access_key";
var transId = "Trans123";
var transactionSrc = "upstest";
var url = "https://wwwcie.ups.com/ship/v1807/shipments";
var header = {
'AccessLicenseNumber' : accessKey,
'password' : password,
'transId' : transId,
'transactionsrc' : transactionSrc,
'username' : userName
};
// parameters for url fetch
var params = {
'method': 'GET',
'contentType': 'application/json',
'headers': header,
'payload' : JSON.stringify(payload)
};
// call the UPS Shipment API
var response = UrlFetchApp.fetch(url, params);
}
Not including the JSON payload here

Answer 1

Answer:
UrlFetchApp() has functionality and response limitations, including POST and response sizes.
More Information:
As per the Apps Script Documentation, URL Fetch has Limitations which are implemented in the methods themselves. The limitations are as follows:
URL Fetch response size: 50MB/call
URL Fetch headers: 100/call
URL Fetch header size: 8kB/call
URL Fetch POST size: 50MB/call
URL Fetch URL length: 2kB/call
Unfortunately, there is no way to get around this.
Feature Request:
There is a Feature Request on Google's Issue Tracker requesting the increase of the UrlFetch response size limit already. This Feature Request can be found here, which you can give a star (☆) in the top left to let Google know more people wish for this request. There is already a response from them saying 'We'll consider raising the quota if there is enough interest from the developer community.', so letting them know this is a wanted feature is a good way to go.
References:
Google's Issue Tracker
Increase the UrlFetch Total Bytes quota Feature Request
Quotas for Google Services
Current Quotas
Current Limitations