feat: make fusion API more similar to flow API

make fusion API to use MenuItems instead of DTOs so it's more similar to flow API

Author: mlopezFC

src/main/java/com/flowingcode/addons/applayout/MenuItem.java

@@ -115,6 +115,10 @@ public String getLabel() {
     return getElement().getAttribute("label");
   }
 
+  public String getHref() {
+    return getElement().getProperty("href");
+  }
+
   public MenuItem setLabel(String label) {
     getElement().setAttribute("label", label);
     return this;

src/main/java/com/flowingcode/addons/applayout/endpoint/MenuEndpoint.java

@@ -3,6 +3,7 @@
 import java.util.List;
 import java.util.stream.Collectors;
 
+import com.flowingcode.addons.applayout.MenuItem;
 import com.vaadin.flow.server.auth.AnonymousAllowed;
 import com.vaadin.flow.server.connect.Endpoint;
 
@@ -17,7 +18,16 @@ public MenuEndpoint(List<MenuItemsProvider> menuItemsProviders) {
     }
 
     public List<MenuItemDto> getMenuItems() {
-        return menuItemsProviders.stream().map(mip->mip.getMenuItems()).flatMap(List::stream).collect(Collectors.toList());
+        List<MenuItem> menuItems = menuItemsProviders.stream().map(MenuItemsProvider::getMenuItems).flatMap(List::stream).collect(Collectors.toList());
+        return convertMenuItems(menuItems);
+    }
+
+    private List<MenuItemDto> convertMenuItems(List<MenuItem> menuItems) {
+        return menuItems.stream().map(mi->new MenuItemDto(mi.getLabel(),mi.getHref(),extractMenuItems(mi))).collect(Collectors.toList());
+    }
+
+    private List<MenuItemDto> extractMenuItems(MenuItem mi) {
+        return convertMenuItems(mi.getChildren().filter(MenuItem.class::isInstance).map(MenuItem.class::cast).collect(Collectors.toList()));
     }
 
 }

src/main/java/com/flowingcode/addons/applayout/endpoint/MenuItemsProvider.java

@@ -2,9 +2,11 @@
 
 import java.util.List;
 
+import com.flowingcode.addons.applayout.MenuItem;
+
 @FunctionalInterface
 public interface MenuItemsProvider {
 
-    List<MenuItemDto> getMenuItems();
+    List<MenuItem> getMenuItems();
 
 }