BAEL-8841 Merge vaadin and vaadin-spring

- Moved vaadin-spring code to vaadin module

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

@@ -0,0 +1,10 @@
+package com.baeldung;
+
+import java.util.List;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface EmployeeRepository extends JpaRepository<Employee, Long> {
+
+    List<Employee> findByLastNameStartsWithIgnoreCase(String lastName);
+}