public class ABoringTestClass
{
    public class Class1
    {
        private ContainerContainer container = new ContainerContainer();

        public void function1()
        {
            container.list.add(new DuckContainer());
            Object duck = container.list.get(0).getItem();
        }
    }

    public class ContainerContainer
    {
        public List<IContainer> list = new List<IContainer>;
    }

    public interface IContainer<T>
    {
        T getItem();
    }

    public class DuckContainer implements IContainer<Duck>
    {
        private Duck duck = new Duck();

        public Duck getItem()
        {
            return duck;
        }
    }

    public class Duck
    {
    }
}