Code quality fixes

Author: javier-godoy

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

@@ -21,7 +21,6 @@
 
 import java.util.Optional;
 
-import com.flowingcode.addons.applayout.AppLayout;
 import com.vaadin.flow.component.AttachEvent;
 import com.vaadin.flow.component.HasElement;
 import com.vaadin.flow.component.html.Div;
@@ -73,7 +72,7 @@ protected void showRouterLayoutContent(AppLayout app, HasElement content) {
 		RouterLayout.super.showRouterLayoutContent(content);
 	}
 
-	private String getCaption(HasElement content) {
+	private static String getCaption(HasElement content) {
 		if (content instanceof HasDynamicTitle) {
 			return ((HasDynamicTitle)content).getPageTitle();
 		} else {

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

@@ -52,7 +52,7 @@
 @CssImport("./styles/applayout-styles.css")
 public class AppLayout extends Div implements PageConfigurator {
 
-	final static String NPM_VERSION = "3.0.2";
+	static final String NPM_VERSION = "3.0.2";
 
 	AppDrawer drawer;
 	AppHeader header;

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

@@ -60,7 +60,7 @@ public AppToolbar(String title, AppDrawer drawer) {
 
     public AppToolbar(Image logo, String title, AppDrawer drawer) {
     	menu = new PaperIconButton("menu");
-    	menu.getElement().setAttribute("onclick", "" + drawer.getId().get() + ".toggle()");
+    	drawer.getId().ifPresent(id -> menu.getElement().setAttribute("onclick", id + ".toggle()"));
     	this.add(menu);
     	if (logo!=null) {
     		ctitle = logo;

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

@@ -41,14 +41,15 @@ public CollapseButton(String label, PaperItem[] items) {
 		this(label, null, null, items);
 	}
 
+	@SuppressWarnings("squid:S2589")
 	public CollapseButton(String label, String icon, String image, Component...items) {		
 		if (icon==null && image==null) {
 			PaperItem pi = new PaperItem(label);
 			configureAndAddItem(pi);
-		} else if(image!=null) {
+		} else if (image!=null) {
 			PaperIconItem pi = new PaperIconItem(label, image);
 			configureAndAddItem(pi);
-		} else if(icon!=null) {
+		} else if (icon!=null) {
 			PaperIconItem pi = new PaperIconItem(label, icon);
 			configureAndAddItem(pi);
 		}