Java generics converting Future of list of concrete class to future of list of interface?

Java generics converting Future of list of concrete class to future of
list of interface?

I'm trying to convert a Future of List of Concrete classes into a future
of List of Interfaces, but I get an "incompatible types" error when I try
it. Basically my code looks something like this
public void main()
{
Future<List<ConcreteClass>> future = getFutureStuff();
doStuffWithInferface(future); // Syntax Error!
}
public void doStuffWithInterface(Future<List<InterfaceClass>>)
{
blah();
}
Is there a good way to change this without changing the getFutureStuff
signature to
public Future<? extends List<? extends InterfaceClass>> getFutureStuff();
and littering my code with ? extends InterfaceClass.