Added Subtitle option

Author: aripddev

chartjs-java-model/src/main/java/software/xdev/chartjs/model/options/Plugins.java

@@ -20,6 +20,7 @@
 public class Plugins
 {
 	protected Title title;
+	protected Title subtitle;
 	protected Legend legend;
 	protected Tooltip tooltip;
 	protected Zoom zoom;
@@ -41,6 +42,22 @@ public Plugins setTitle(final Title title)
 		this.title = title;
 		return this;
 	}
+
+	/**
+	 * @see #setSubtitle(Title)
+	 */
+        public Title getSubtitle() {
+          return this.subtitle;
+        }
+
+	/**
+	 * The subtitle configuration is passed into the options.subtitle namespace. The global options for the chart subtitle is
+	 * defined in Chart.defaults.global.subtitle.
+	 */
+        public Plugins setSubtitle(Title subtitle) {
+          this.subtitle = subtitle;
+          return this;
+        }
 
 	/**
 	 * @see #setLegend(Legend)