[xwiki-users] Using the user list property in a query?

Is it possible to use the User List property in a query? For some reason I can't seem to get it to return in a query (other property types I use eg numerics/strings/dblist I can return with their respective type). Is it perhaps stored as a different type to StringProperty? If so, what is it's type (and is there any "gotcha's" to using it in a query)?