Hi Kumar,
I just tried and it's working for me. Below are the steps I used to make it work.
1. I created a webhook listener in IO and provided the necessary details. For the Key (secret) value, I used: "secret".
2. I entered the POST public URL in Postman and used the script mentioned in the earlier post.
3. In the above screenshot, I defined the HMAC variable using the same script I'm using in the Pre-request Script, as shown in the screenshot below.
4. I received a 204 response code and was able to see the data in IO.
Hope this helps.
Thanks,
Om Mishra