HTTPS Connector

I’m struggling to build a connector to a Keycloak Open ID Connect service. Trying to use the HTTPS connector with a formula to construct the x-www-form-urlencoded body

First I tried just sending the body credentials - but that is giving me an error on keycloak that it doesn’t recognise client credentials so then I thought that it must need each of the items listed out as name value pairs… the above is my attempt at doing that but I can’t get this to validate. I think it’s something to do with the ‘Body’ at the beginning. I’ve tried replacing this with various App variables… no joy. Could someone with a wiser head please help me with what I’m doing wrong?

Many thanks for taking the time to look at this.