Facebook Messenger Bot welcome message: 100 Parameter_type required

Question

I want to make my dialogflow bot talk first. Following the documentation, I am trying to set up a welcome message for a Facebook Messenger bot using the code provided in the documentation - with my own Page ID and Page access token:

But it returns:

{
    "error": {
        "message": "(#100) Requires one of the params: get_started,persistent_menu,target_audience,whitelisted_domains,greeting,account_linking_url,payment_settings,home_url,ice_breakers",
        "type": "OAuthException",
        "code": 100,
        "fbtrace_id": "AcX40py3Er1_YoPYdL5G901"
    }
}