@Override
    public boolean hasNext()
    {
        if (startingItem == null)
        {
            return false;
        }
        if (currentItem == null)
        {
            return true;
        }
        PDOutlineItem sibling = currentItem.getNextSibling();
        return sibling != null && !startingItem.equals(sibling);
    }
@Test
    void noChildren()
    {
        PDOutlineItemIterator iterator = new PDOutlineItemIterator(null);
        assertFalse(iterator.hasNext());
    }