plot1.setPaint(new GradientPaint(1.0f, 2.0f, Color.red, 
                3.0f, 4.0f, Color.yellow));
        assertFalse(plot1.equals(plot2));
        plot2.setPaint(new GradientPaint(1.0f, 2.0f, Color.red, 
                3.0f, 4.0f, Color.yellow));
        assertTrue(plot1.equals(plot2));