[JAVA-27510] Upgrade vaadin to boot 3 (#16122)

Author: vunamtien

vaadin/pom.xml

@@ -11,9 +11,9 @@
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>parent-boot-2</artifactId>
+        <artifactId>parent-boot-3</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-boot-2</relativePath>
+        <relativePath>../parent-boot-3</relativePath>
     </parent>
 
     <dependencyManagement>
@@ -32,6 +32,7 @@
         <dependency>
             <groupId>javax.servlet</groupId>
             <artifactId>javax.servlet-api</artifactId>
+            <version>4.0.1</version>
             <scope>provided</scope>
         </dependency>
         <dependency>

vaadin/src/main/java/com/baeldung/Employee.java

@@ -1,8 +1,8 @@
 package com.baeldung;
 
-import javax.persistence.Entity;
-import javax.persistence.GeneratedValue;
-import javax.persistence.Id;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
 
 @Entity
 public class Employee {

vaadin/src/main/java/com/baeldung/introduction/VaadinUI.java

@@ -8,8 +8,6 @@
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
-import javax.servlet.annotation.WebServlet;
-
 import com.vaadin.annotations.Push;
 import com.vaadin.annotations.Theme;
 import com.vaadin.annotations.VaadinServletConfiguration;
@@ -41,6 +39,7 @@
 import com.vaadin.ui.TwinColSelect;
 import com.vaadin.ui.UI;
 import com.vaadin.ui.VerticalLayout;
+import jakarta.servlet.annotation.WebServlet;
 
 @SuppressWarnings("serial")
 @Push