Java has a hmac support: https://www.baeldung.com/java-hmac
You could use Groovy script test step to calculate hmac from request payload.
I have not personally used HMAC but I could find this site that describe HMAC process and how it works in general level: https://dotnettutorials.net/lesson/hmac-authentication-web-api/
You just have to follow a client process with SoapUI requests and then do required calculations by utilizing groovy scripts.
I have already tried the groovy approach, but I am unable to make that work as I have a consumer secret and a token secret (this is what postman uses) from the client instead of the secret key.