The user id of the user. You can also use certain other values by changing the value_type argument.
You can choose between certain value types. Possible: id, slug, email, login
Advanced: Register a custom action after the plugin fires this webhook.
(String) Register a custom WordPress hook callback. The value will be called as followed: do_action( $yourdefinedaction, $action_return_data, $request_data )
More available WordPress endpoints
To learn more about a specific endpoint, simply click on it.