How can I pass the Session ID in API Request via Apps Script? - api

Question

I am trying to access the API of our CRM Documentation through Google Sheets / Apps Script.
When accessing the API through Postman I have no issues and get the desired results using the following setup:
POST: https://api.sharpspring.com/pubapi/v1.2/?accountID={{accountID}}&secretKey={{secretKey}}
BODY:
{
"id":"12345678912345678999",
"method": "getOpportunities",
"params": {
"where": {},
"limit":"500",
"offset": "0"
}
}
Now, when I try to replicate the same in Apps Script I get the following result:
{ result: null,
error: { code: 102, message: 'Header missing request ID', data: [] },
id: null }
The function that I am running is as below:
function myFunction() {
var URL = "https://api.sharpspring.com/pubapi/v1.2/?accountID={{accountID}}&secretKey={{secretKey}}"
var body = {
"method": "POST",
"body": raw,
"headers": {"Content-Type": "application/json"},
"redirect": "follow"
}
var raw = {
"method": "getOpportunities",
"id": "12345678912345678999",
"params": {
"where": {},
"limit":"500",
"offset": "0"
}
}
var results = UrlFetchApp.fetch(URL, body).getContentText();
var data = JSON.parse(results);
console.log(data);
}
In both I am passing a random session ID "12345678912345678999". I tried finding a session ID in the cookie but that didn't work and I assume that I am on the wrong path there. Passing the id in the header directly didn't work either.
Any ideas? Thanks a lot in advance!