reset ThemeChart02

xchart-demo/src/main/java/org/knowm/xchart/demo/charts/theme/ThemeChart02.java

@@ -45,7 +45,7 @@ public class ThemeChart02 implements ExampleChart {
   public Chart getChart() {
 
     // Create Chart
-    Chart_XY chart = new ChartBuilder_XY().width(800).height(600).theme(ChartTheme.Matlab).title("Matlab Theme").xAxisTitle("X").yAxisTitle("Y").build();
+    Chart_XY chart = new ChartBuilder_XY().width(800).height(600).theme(ChartTheme.GGPlot2).title("GGPlot2 Theme").xAxisTitle("X").yAxisTitle("Y").build();
 
     // Customize Chart