fix: move chart initialization to onAttach method

Close #37

Author: paodb

src/main/java/com/flowingcode/vaadin/addons/orgchart/OrgChart.java

@@ -23,6 +23,7 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.flowingcode.vaadin.addons.orgchart.client.OrgChartState;
+import com.vaadin.flow.component.AttachEvent;
 import com.vaadin.flow.component.ClientCallable;
 import com.vaadin.flow.component.ComponentEvent;
 import com.vaadin.flow.component.ComponentEventListener;
@@ -66,13 +67,24 @@ public OrgChart(OrgChartItem orgChartItem) {
     this.setId(identifier);
   }
 
-  public void initializeChart() {
-    String identifier = "orgchart" + this.hashCode();
+  @Override
+  protected void onAttach(AttachEvent attachEvent) {
+    super.onAttach(attachEvent);
     this.getElement()
         .executeJs(
-            "this.initializeOrgChart($0,$1,$2)", convertToJsonObj(state), state.value, identifier);
+            "this.initializeOrgChart($0,$1,$2)",
+            convertToJsonObj(state),
+            state.value,
+            this.getId().get());
   }
 
+  /**
+   * @deprecated This method is no longer needed. Initialization is done in {@link
+   *     #onAttach(AttachEvent)}.
+   */
+  @Deprecated
+  public void initializeChart() {}
+
   public void setValue(OrgChartItem orgChartItem) {
     String value = convertToJsonObj(orgChartItem);
     getState().value = value;

src/test/java/com/flowingcode/vaadin/addons/orgchart/BottomTopDemo.java

@@ -32,7 +32,6 @@ public BottomTopDemo() {
     component2.setChartTitle("My Organization Chart Demo - Example 2 - BOTTOM TO TOP DIRECTION");
     component2.setChartNodeContent("title");
     component2.setChartDirection(ChartDirectionEnum.BOTTOM_TO_TOP.getAbreviation());
-    component2.initializeChart();
 
     setSizeFull();
     add(component2);

src/test/java/com/flowingcode/vaadin/addons/orgchart/DragAndDropExportDemo.java

@@ -19,10 +19,11 @@
  */
 package com.flowingcode.vaadin.addons.orgchart;
 
+import java.util.Arrays;
+
 import com.flowingcode.vaadin.addons.orgchart.extra.TemplateLiteralRewriter;
 import com.vaadin.flow.component.notification.Notification;
 import com.vaadin.flow.component.orderedlayout.VerticalLayout;
-import java.util.Arrays;
 
 @SuppressWarnings("serial")
 public class DragAndDropExportDemo extends VerticalLayout {
@@ -42,7 +43,6 @@ public DragAndDropExportDemo() {
     component1.setChartExportButton(true);
     component1.setChartExpandCollapse(true);
     component1.setChartDraggable(true);
-    component1.initializeChart();
     component1.addDragAndDropListener(
         e ->
             System.out.println(