Facebook send request to node webhook infinite request

I am working on a chatbot using node app as a webhook and Facebook messenger as a chat application. I have created an endpoint in the swagger.yaml. Facebook messenger sends the request to this endpoint in an infinite loop. I am very new to swagger. I have created another simple app without swagger and Facebook messenger and its working fine. But with the swagger Facebook request are coming in an infinite loop. I think there is some issue with swagger endpoint configuration

Any help on this will be appreciated.