403 Forbidden Error in OIC When Calling External Token API (Works in Postman)

Hi All,

I am trying to invoke external REST endpoint to generate a token for MenaiTech. I was successfully able to invoke from POSTMAN. Attached is the screenshot of how i invoked from postman and I am trying to replicate the same from OIC. Here are the steps i followed.

1. I invoked from postman and took URL from postman.

2. I Create REST adapter and no security policy and configured and have tested successfully. as shown screenshot.

1. I configured the request body as a query parameter and then enable(Send query parameters as form data in message) body option.
   Below is the error i am getting when i am trying to invoke.