It would be the other way around. You wouldn't pass around the underlying suppliers directly, you'd wrap them. But if you must have state _and_ behavior, then

It would be the other way around. You wouldn't pass around the underlying suppliers directly, you'd wrap them. But if you must have state _and_ behavior, then `abstract class` is your friend in Java (while in Scala traits can have fields and constructors, so there is no problem).