NVL function to use in Jasper Domain calculated field

In the Oracle query I have a field "NVL(SOUP1.ORG_NAME, SEC.AGENT_BANK) as agent".

I'd like to evaluate this expression into calculated field in Jasper Domain. Can I use an existing key isNull from "applicationContext-semanticLayer.xml" file in Jasper Domain or I have to create new entry for that? If I need to create new one - what's the language to create it? Is any example available?