BAEL-1533 Making a Spring MVC Form Remember Values

- add example code
- update pom dependency to spring boot starter 2.0.0.RC2
- update import in SpringApplicationException

spring-5/src/main/java/com/baeldung/sessionattrs/TodoControllerWithSessionAttributes.java

@@ -0,0 +1,55 @@
+package com.baeldung.sessionattrs;
+
+import java.time.LocalDateTime;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.ModelAttribute;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.SessionAttributes;
+import org.springframework.web.servlet.mvc.support.RedirectAttributes;
+import org.springframework.web.servlet.view.RedirectView;
+
+@Controller
+@RequestMapping("/sessionattributes")
+@SessionAttributes("todos")
+public class TodoControllerWithSessionAttributes {
+
+    @GetMapping("/form")
+    public String showForm(
+            Model model,
+            @ModelAttribute("todos") TodoList todos) {
+        if (!todos.isEmpty()) {
+            model.addAttribute("todo", todos.peekLast());
+        } else {
+            model.addAttribute("todo", new TodoItem());
+        }
+        return "sessionattributesform";
+    }
+
+    @PostMapping("/form")
+    public RedirectView create(
+            @ModelAttribute TodoItem todo, 
+            @ModelAttribute("todos") TodoList todos, 
+            RedirectAttributes attributes) {
+        todo.setCreateDate(LocalDateTime.now());
+        todos.add(todo);
+        attributes.addFlashAttribute("todos", todos);
+        return new RedirectView("/sessionattributes/todos.html");
+    }
+
+    @GetMapping("/todos.html")
+    public String list(
+            Model model, 
+            @ModelAttribute("todos") TodoList todos) {
+        model.addAttribute("todos", todos);
+        return "sessionattributestodos";
+    }
+
+    @ModelAttribute("todos")
+    public TodoList todos() {
+        return new TodoList();
+    }
+}