DefaultMultiValueCategoryDataset d 
                = new DefaultMultiValueCategoryDataset();
        assertTrue(d.getRowCount() == 0);
        List values = new ArrayList();
        d.add(values, "R1", "C1");
        assertTrue(d.getRowCount() == 1);
        
        d.add(values, "R2", "C1");
        assertTrue(d.getRowCount() == 2);