This only shows you for which role you have signed up, not which role any other player has been assigned to. Neither to which role you have been assigned to.
I suppose that's not what he wants... Anyway he could be more specific on his question...
Alright to be more specific. In my CC I want to get the WoWPlayer who has the tank role in my current group.
This is so I can prevent my char from casting Hand of Protection on the tank
I know this part of HB's api contains it, but I'm not sure how to compare with a specific WoWUnit: