[4.6.4] REST: How are the PLAIN parameters used?

Somebody created a Groovy script that looks as if it could do what I want:
viewtopic.php?t=11065#p43576

Is there a way to check what type a parameter is, e.g. PLAIN, so I don't have to insert them all into my message's body?
The relevant ENUM to compare against seems to be this one: http://www.soapui.org/apidocs/com/eviwa ... Style.html
But I have no clie how to access a property's "Style" (e.g. PLAIN), let alone how to check against it...

Brgrds,

Christian