IssueTracker

Please provide a short description of the issue:

There is no source field for form submit event created by onFormSubmit() of FormTriggerBuilder in a standalone script.
If a script is bound to a spreadsheet, a source field appears.
However, it does not contain Form object but the Spreadsheet object.

Please provide a small sample script that reliably reproduces the issue.
The sample should run as-is or with minimal setup, without external
dependencies.

function myFunction() {
  var form = FormApp.openById("a form id");
  ScriptApp.newTrigger("onFormSubmitTest").forForm(form).onFormSubmit().create();
}

function onFormSubmitTest(e){
  Logger.log(e);
  MailApp.sendEmail("mail address", "report", Logger.getLog());
}

What steps will reproduce the problem?
1. make a form
2. make a standalone blank script, write the above script, and run myFunction to make a trigger for the form
3. respond the form.

What is the expected output? What do you see instead?

Accourding to

https://developers.google.com/apps-script/guides/triggers/events#google_forms_events

the output in mail should be

{response=FormResponse, source=Form, authMode=FULL},

but the actual output in mail is

{response=FormResponse, authMode=FULL}.


What is the project key (found under "File > Project properties")? The
project key does not give the Apps Script team access to your source
code or data. We use it to look up debug information about your script.
       
MbhzuVtZwb4GCealMFUsrJ68VJNknFO53


Please provide any additional information below.

When I make the same script as one bound to a spreadsheet, source field appears but it contains not the form object but the spreadsheet object.


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