How to perform JSON based authentication with Nessus?

Question

I'm trying to configure credentials to do a authenticated scan of a web application on the HTTP Login Form.

The application use json parameters to send the credentials, i'm using the "HTTP login form" but the login ends up failing all the time.

The application send the credentials via a POST request like so : {username: "user", password: "password"}

So as "Login parameters" I put : {username: "user", password: "password"}

After I run the scan I get the message "HTTP Login failed; post authenticaton failed". Would someone be able to point me in the right direction, please?

Thanks!