Maniphest.edit getting "transactions\" is not a list of transactions."

I am trying to implement the maniphest.edit in javascript (google script). Below is the code. And I am getting “transactions” is not a list of transactions.". Anyone can shed some light?

var payload = {
    "api.token": PHAB_TOKEN,
    transactions: [{"type": "title", "value": "test"}],
    output: 'json'
  };
  
  var options = {
    method: 'post',
    payload: payload,
  };
  
  var resp = UrlFetchApp.fetch("https://xxxxxxx/api/maniphest.edit", options);

This appears to be a copy of https://discourse.phabricator-community.org/t/creating-new-maniphest-task-with-javascript/2816, so I’m going to lock it. Please don’t make multiple copies of the same thread.