How to avoid unchecked cast warning in my generic recursive Iterator in Java

Somewhat odd that Java's collection framework has no iterator for recursive data structures... Since I needed something like this, I wrote my own. First of I need recursive elements:

public interface RecursiveElement<T>
{
    public Iterator<T> getChildrenIterator();
}

And then an Iterator:

public class RecursiveIterator<T> implements Iterator<T>
{
    private Deque<Iterator<T>> stack;
    private Iterator<T> currentStackItem;

    /**
     * Creates a new instance
     * 
     * @param root
     *            all children of this node are iterated. The root node itself
     *            is not returned
     * @throws NullPointerException
     *             if root is null
     */
    public RecursiveIterator(final RecursiveElement<T> root)
    {
        if (root == null)
            throw new NullPointerException(
                    "root argument to this iterator must not be null");
        stack = new LinkedList<Iterator<T>>();
        currentStackItem = root.getChildrenIterator();
    }

    @Override
    public boolean hasNext()
    {
        return currentStackItem != null;
    }

    @Override
    public T next()
    {
        final T result = currentStackItem.next();
        if (result instanceof RecursiveElement)
        {
            stack.addLast(currentStackItem);
             // Here is the warning:
            currentStackItem = ((RecursiveElement<T>)result).getChildrenIterator();
        }
        while (currentStackItem != null && !currentStackItem.hasNext())
            currentStackItem = stack.pollLast();
        return result;
    }

    @Override
    public void remove()
    {
        currentStackItem.remove();
    }
}

That code works very well, but I do get a warning from the compiler in the next() method in the line I marked. It is clear to me why this warning occurs, but I have not come up with any solution on how to solve the problem without this warning (save suppressing the warning). Any ideas?