ADD:: added javadoc comments where needed for the checkstyle

EDIT:: edited some lines to fit the checkstyle

fixed some indentation warnings and line length warnings

src/Server/src/main/java/gogreen/server/data/model/User.java

@@ -20,20 +20,38 @@ public class User {
     String name;
     String password;
 
+    /**
+     * makes a user object.
+     * @param id the id of the user.
+     * @param name the supplied username
+     * @param password the supplied password
+     */
     public User(Long id, String name, String password) {
         this.id = id;
         this.name = name;
         this.password = password;
     }
 
+    /**
+     * gets the id.
+     * @return the id
+     */
     public Long getId() {
         return id;
     }
 
+    /**
+     * gets the name.
+     * @return the name
+     */
     public String getName() {
         return name;
     }
 
+    /**
+     * gets the password.
+     * @return the password
+     */
     public String getPassword() {
         return password;
     }

src/Server/src/main/java/gogreen/server/rest/RestExceptionHandler.java

@@ -11,7 +11,7 @@ import org.springframework.web.bind.annotation.RestControllerAdvice;
 public class RestExceptionHandler {
     @ExceptionHandler(ApplicationException.class)
     @ResponseStatus(HttpStatus.BAD_REQUEST)
-    public ErrorResponse applicationException (ApplicationException ex) {
+    public ErrorResponse applicationException(ApplicationException ex) {
         return new ErrorResponse(ex.getMessage());
     }
 }

src/Server/src/main/java/gogreen/server/rest/UserController.java

@@ -13,14 +13,14 @@ public class UserController {
     UserService userService;
 
     @RequestMapping("/registerUser")
-    public UserDTO registerUser(@RequestParam(value="name") String name,
-                                @RequestParam(value="password") String password) {
+    public UserDTO registerUser(@RequestParam(value = "name") String name,
+                                @RequestParam(value = "password") String password) {
         return userService.registerUser(name, password);
     }
 
     @RequestMapping("/login")
-    public UserDTO login(@RequestParam(value="name") String name,
-                         @RequestParam(value="password") String password) {
+    public UserDTO login(@RequestParam(value = "name") String name,
+                         @RequestParam(value = "password") String password) {
         return userService.login(name, password);
     }
 }

src/Server/src/main/java/gogreen/server/service/UserService.java

@@ -15,6 +15,12 @@ public class UserService {
     @Autowired
     UserRepository userRepository;
 
+    /**
+     * registers the user.
+     * @param name the username of the user
+     * @param password the password of the user
+     * @return a userDTO of the registered user
+     */
     public UserDTO registerUser(String name, String password) {
         User user = userRepository.findByName(name);
         if (user != null) {
@@ -26,6 +32,12 @@ public class UserService {
         return new UserDTO(user.getId(), user.getName());
     }
 
+    /**
+     * logs the user in.
+     * @param name the username of the user
+     * @param password the password of the user
+     * @return a userDTO of the logged in user
+     */
     public UserDTO login(String name, String password) {
         User user = userRepository.findByName(name);
         if (user == null) {