Permission error using UrlFetchApp in Gmail add-on

Question

I am just starting to try to create a new Gmail add-in and am running the following error message:

"You do not have permission to call fetch"

This happens when testing addin in the script editor, as well as when deploying inside my Gmail. Here is a sample code:

function getContextualAddOn(e) {
    var API_KEY = 'TESTKEY';
    var URL = 'https://[REDACTED]';
    var options = {
        'method' : 'post',
        'contentType': 'application/json',
        'headers': {
            'x-api-key': API_KEY
        },
        'payload' : JSON.stringify({ 'foo': 'bar' })
    };

    var response = UrlFetchApp.fetch(URL, options);

    [more code that builds a card] 
}

As you can see, this is a fairly simple use of UrlFetchApp.fetch. I'm new to AppsScript, so maybe I missed the declaration or permission area in my manifest. I tried an even simpler example using UrlFetchApp.getRequest, but that also failed: "You do not have permission to call getRequest."

the manifest for the addon is the same as in the examples:

{
  "timeZone": "America/New_York",
  "dependencies": {
  },
  "exceptionLogging": "STACKDRIVER",

  "oauthScopes": [
    "https://www.googleapis.com/auth/gmail.addons.execute","https://www.googleapis.com/auth/gmail.addons.current.message.readonly",    "https://www.googleapis.com/auth/userinfo.email"
  ],
  "urlFetchWhitelist": [
    "https://[REDACTED]"
  ],
  "gmail": {
    "name": "Test Add-On",
    "logoUrl": "https://www.gstatic.com/images/icons/material/system/1x/receipt_black_24dp.png",
    "primaryColor": "#4285F4",
    "secondaryColor": "#4285F4",
    "contextualTriggers": [{
      "unconditional": {},
      "onTriggerFunction": "getContextualAddOn"
    }],
    "version": "TRUSTED_TESTER_V2"
  }
}

, UrlFetchApp Gmail Add-On, ? - - script?

Answer 1

UrlFetchApp , https://www.googleapis.com/auth/script.external_request. . , , oauthScopes > a > .