Fix checkstyle issues in SparkJava demo

managedvms/sparkjava/pom.xml

@@ -84,9 +84,6 @@
         <configuration>
         </configuration>
       </plugin>
-      <!--
-           The SparkJava demo currently (2016-01-22) fails the Google Style
-           checks. We can uncomment this block when it is fixed.
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-checkstyle-plugin</artifactId>
@@ -101,7 +98,6 @@
           <execution><goals><goal>check</goal></goals></execution>
         </executions>
       </plugin>
-      -->
     </plugins>
   </build>
 </project>

managedvms/sparkjava/src/main/java/com/google/appengine/sparkdemo/Main.java

@@ -22,6 +22,9 @@
 
 public class Main {
 
+  /**
+   * Starts the webapp on localhost:8080.
+   */
   public static void main(String[] args) {
     port(8080);
     UserController userController =

managedvms/sparkjava/src/main/java/com/google/appengine/sparkdemo/ResponseError.java

@@ -24,7 +24,7 @@ public ResponseError(String message, String... args) {
     this.message = String.format(message, (Object) args);
   }
 
-  public ResponseError(Exception e) {
-    this.message = e.getMessage();
+  public ResponseError(Exception ex) {
+    this.message = ex.getMessage();
   }
 }

managedvms/sparkjava/src/main/java/com/google/appengine/sparkdemo/User.java

@@ -24,10 +24,16 @@ public class User {
   private String name;
   private String email;
 
+  /**
+   * Construct a user given a name and email. An ID is auto-generated for the user.
+   */
   public User(String name, String email) {
     this(UUID.randomUUID().toString(), name, email);
   }
 
+  /**
+   * Construct a user given an ID, name, and email.
+   */
   public User(String id, String name, String email) {
     this.id = id;
     this.email = email;

managedvms/sparkjava/src/main/java/com/google/appengine/sparkdemo/UserController.java

@@ -30,6 +30,9 @@
 
 public class UserController {
 
+  /**
+   * Creates a controller that maps requests to gcloud-java functions.
+   */
   public UserController(final UserService userService) {
     Spark.staticFileLocation("/public");
 
@@ -48,13 +51,13 @@ public UserController(final UserService userService) {
     delete("/api/users/:id", (req, res) -> userService.deleteUser(req.params(":id")), json());
 
     after((req, res) -> {
-          res.type("application/json");
-        });
+      res.type("application/json");
+    });
 
-    exception(IllegalArgumentException.class, (e, req, res) -> {
-          res.status(400);
-          res.body(toJson(new ResponseError(e)));
-        });
+    exception(IllegalArgumentException.class, (error, req, res) -> {
+      res.status(400);
+      res.body(toJson(new ResponseError(error)));
+    });
   }
 
   private static String toJson(Object object) {

managedvms/sparkjava/src/main/java/com/google/appengine/sparkdemo/UserService.java

@@ -38,6 +38,9 @@ public UserService(Datastore datastore) {
     this.datastore = datastore;
   }
 
+  /**
+   * Return a list of all users.
+   */
   public List<User> getAllUsers() {
     Query<Entity> query =
         Query.gqlQueryBuilder(Query.ResultType.ENTITY, "SELECT * FROM " + KINDNAME).build();
@@ -51,6 +54,9 @@ public List<User> getAllUsers() {
     return users;
   }
 
+  /**
+   * Create a new user and add it to Cloud Datastore.
+   */
   public User createUser(String name, String email) {
     failIfInvalid(name, email);
     User user = new User(name, email);
@@ -65,13 +71,19 @@ public User createUser(String name, String email) {
     return user;
   }
 
+  /**
+   * Delete a user from Cloud Datastore.
+   */
   public String deleteUser(String id) {
     KeyFactory keyFactory = datastore.newKeyFactory().kind(KINDNAME);
     Key key = keyFactory.newKey(id);
     datastore.delete(key);
     return "ok";
   }
 
+  /**
+   * Updates a user in Cloud Datastore.
+   */
   public User updateUser(String id, String name, String email) {
     failIfInvalid(name, email);
     KeyFactory keyFactory = datastore.newKeyFactory().kind(KINDNAME);