Google Scripts API - autoUpdateForwarding Not Applying - google-apps-script

Question

As Domain Admin for the company I work at we'd like to set the forwarding addresses of staff as they leave the company to ensure any important correspondence isn't missed.
I've used the Google Apps OAuth2 Library successfully so far, but come across a snag. The following code is meant to forward emails from the address apitest#example.com to newaddress#example.com .
function setupForwarding() {
var service = getOAuthService();
service.reset();
try {
if (service.hasAccess()) {
var header = {
Authorization: 'Bearer ' + service.getAccessToken(),
}
var url = "https://www.googleapis.com/gmail/v1/users/apitest#example.com/settings/autoForwarding";
var response = UrlFetchApp.fetch(url, {
headers: header,
method: 'put',
enabled: true,
emailAddress: 'newaddress#example.com',
disposition: 'trash'
});
Logger.log(response.getContentText());
}
} catch (e) {
Logger.log(e.message);
}
}
The access token provided appears to work with other queries provided by UrlFetchApp such as using it to return the currently authorised forwarding addresses recorded on the account (which does include newaddress#example.com) and doesn't report any access priviledge errors. The response returns only the following
{ "enabled" : false }
And does not apply any forwarding. Would someone be able to help me identify the problem? I feel I might be passing the parameters to the HTTP request incorrectly but I'm still learning my way around that system and no other questions I found seemed to help.
Ozzie

Answer 1

I worked this out and it was simpler than I thought; so sharing the answer here in case anyone has a similar issue.
var response = UrlFetchApp.fetch(url, {
headers: header,
method: 'put',
contentType : 'application/json',
payload: '{ "enabled" : "true" , "emailAddress" : "newaddress#example.com" , "disposition" : "trash" }'
});
Is the functional way to do this; the request was expecting a separate payload and declared content type both.