What are the default user agent and other headers sent by New Relic Synthetic and how to set it to my need?

Dear Sir/Madam,
Have a nice day!
I have a question to inquire you about newrelic synthetic monitoring.
What are the default user agent and other headers sent by New Relic synthetic and how to set it to my need?
The website I’m testing is UserAgent restricted. So in my test code, I need to set USER_AGENT to
“Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”.
I referenced the code writting by the following link, but it does not work for me.
https://docs.newrelic.com/docs/new-relic-solutions/best-practices-guides/full-stack-observability/synthetic-monitoring-best-practices-guide/
This is a part of testing code I tried.

const USER_AGENT = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36"
$headers.add("User-Agent", USER_AGENT)
$webDriver.getCapabilities().then(function (caps) {
  console.log(caps);
})

And when I run that code on newrelic synthetic monitoring, I got the result as the following.

Capabilities {
	map_: Map(16) {
		'acceptInsecureCerts' => false,
		'browserName' => 'chrome',
		'browserVersion' => '100.0.4896.60',
		'chrome' => {
		chromedriverVersion: '99.0.4844.51 (d537ec02474b5afe23684e7963d538896c63ac77-refs/branch-heads/4844@{#875})',
		userDataDir: '/tmp/.com.google.Chrome.5dBEtn'
	},
	'goog:chromeOptions' => { debuggerAddress: 'localhost:34401' },
	'networkConnectionEnabled' => false,
	'pageLoadStrategy' => 'eager',
	'platformName' => 'linux',
	'proxy' => {},
	'setWindowRect' => true,
	'strictFileInteractability' => false,
	'timeouts' => { implicit: 0, pageLoad: 300000, script: 30000 },
		'unhandledPromptBehavior' => 'dismiss and notify',
		'webauthn:extension:credBlob' => true,
		'webauthn:extension:largeBlob' => true,
	'webauthn:virtualAuthenticators' => true
	}
}

I’m looking forward to hearing from you.
With regards.

Hi @i-tsumuraya

Thanks for reaching out, I hope you are well.

While this is out of my traditional scope, we want you to know we are working on this.

I have gone ahead and looped in the support engineering team to have a look at this issue. They will reach out via this post with their findings.

Should you have any additional updates or questions please do reach out!

Hi @i-tsumuraya ,

Thanks for contacting New Relic.

That functionality exists on Synthetic Scripted Browser monitors. The exact form of the call will depend on the version you’re using:

There you can find how to access the default headers (to log to the console) and how to set these headers yourself.