Set up Get started button for dialogflow and messenger integration

I am trying to set up a facebook messenger chatbot using dialogflow, and when I am trying to integrate both the services, I get this error message

com.google.dialogflow.bots.common.exceptions.BotWasNotStartedException: Code 400: (#100) You must set a Get Started button if you also wish to use persistent menu.

I tried the method referred in this question : get started button for fb messenger in dialog flow (get started button for fb messenger in dialog flow)

but it threw the error when I tried sending a POST request as given in the answer : "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,platform,title,description,commands", What do I do and how do I proceed from here? Is there a PHP or a JSON code that I must integrate? Or is there something else I can do about it?

Error message in dialogflow while trying to integrate messenger and dialogflow : com.google.dialogflow.bots.common.exceptions.BotWasNotStartedException: Code 400: (#100) You must set a Get Started button if you also wish to use persistent menu.

Error message while trying to send a POST request to set a Get Started button : "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,platform,title,description,commands",