http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepo.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepo.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepo.java
index 92e7b9e..02e5114 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepo.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepo.java
@@ -20,63 +20,62 @@ package org.apache.zeppelin.notebook.repo;
 import java.io.IOException;
 import java.util.List;
 import java.util.Map;
+
+import org.apache.commons.lang.StringUtils;
 import org.apache.zeppelin.annotation.ZeppelinApi;
 import org.apache.zeppelin.conf.ZeppelinConfiguration;
 import org.apache.zeppelin.notebook.Note;
 import org.apache.zeppelin.notebook.NoteInfo;
 import org.apache.zeppelin.user.AuthenticationInfo;
 
-/** Notebook repository (persistence layer) abstraction */
+/**
+ * Notebook repository (persistence layer) abstraction
+ */
 public interface NotebookRepo {
 
   void init(ZeppelinConfiguration zConf) throws IOException;
 
   /**
    * Lists notebook information about all notebooks in storage.
-   *
    * @param subject contains user information.
    * @return
    * @throws IOException
    */
-  @ZeppelinApi
-  public List<NoteInfo> list(AuthenticationInfo subject) throws IOException;
+  @ZeppelinApi public List<NoteInfo> list(AuthenticationInfo subject) throws 
IOException;
 
   /**
    * Get the notebook with the given id.
-   *
    * @param noteId is note id.
    * @param subject contains user information.
    * @return
    * @throws IOException
    */
-  @ZeppelinApi
-  public Note get(String noteId, AuthenticationInfo subject) throws 
IOException;
+  @ZeppelinApi public Note get(String noteId, AuthenticationInfo subject) 
throws IOException;
 
   /**
    * Save given note in storage
-   *
    * @param note is the note itself.
    * @param subject contains user information.
    * @throws IOException
    */
-  @ZeppelinApi
-  public void save(Note note, AuthenticationInfo subject) throws IOException;
+  @ZeppelinApi public void save(Note note, AuthenticationInfo subject) throws 
IOException;
 
   /**
    * Remove note with given id.
-   *
    * @param noteId is the note id.
    * @param subject contains user information.
    * @throws IOException
    */
-  @ZeppelinApi
-  public void remove(String noteId, AuthenticationInfo subject) throws 
IOException;
+  @ZeppelinApi public void remove(String noteId, AuthenticationInfo subject) 
throws IOException;
 
-  /** Release any underlying resources */
-  @ZeppelinApi
-  public void close();
+  /**
+   * Release any underlying resources
+   */
+  @ZeppelinApi public void close();
 
-  /** Versioning API (optional, preferred to have). */
+  /**
+   * Versioning API (optional, preferred to have).
+   */
 
   /**
    * Get NotebookRepo settings got the given user.
@@ -84,8 +83,7 @@ public interface NotebookRepo {
    * @param subject
    * @return
    */
-  @ZeppelinApi
-  public List<NotebookRepoSettingsInfo> getSettings(AuthenticationInfo 
subject);
+  @ZeppelinApi public List<NotebookRepoSettingsInfo> 
getSettings(AuthenticationInfo subject);
 
   /**
    * update notebook repo settings.
@@ -93,6 +91,6 @@ public interface NotebookRepo {
    * @param settings
    * @param subject
    */
-  @ZeppelinApi
-  public void updateSettings(Map<String, String> settings, AuthenticationInfo 
subject);
+  @ZeppelinApi public void updateSettings(Map<String, String> settings, 
AuthenticationInfo subject);
+
 }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoSettingsInfo.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoSettingsInfo.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoSettingsInfo.java
index 4bbf37f..0525502 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoSettingsInfo.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoSettingsInfo.java
@@ -22,13 +22,15 @@ import java.util.Map;
 /**
  * Notebook repo settings. This represent a structure of a notebook repo 
settings that will mostly
  * used in the frontend.
+ *
  */
 public class NotebookRepoSettingsInfo {
 
-  /** Type of value, It can be text or list. */
+  /**
+   * Type of value, It can be text or list.
+   */
   public enum Type {
-    INPUT,
-    DROPDOWN
+    INPUT, DROPDOWN
   }
 
   public static NotebookRepoSettingsInfo newInstance() {

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoSync.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoSync.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoSync.java
index e2c4657..38665ff 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoSync.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoSync.java
@@ -18,8 +18,6 @@
 package org.apache.zeppelin.notebook.repo;
 
 import com.google.common.collect.Lists;
-import java.io.IOException;
-import java.util.*;
 import org.apache.zeppelin.conf.ZeppelinConfiguration;
 import org.apache.zeppelin.conf.ZeppelinConfiguration.ConfVars;
 import org.apache.zeppelin.notebook.Note;
@@ -31,7 +29,14 @@ import org.apache.zeppelin.user.AuthenticationInfo;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Notebook repository sync with remote storage */
+import java.io.IOException;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.util.*;
+
+/**
+ * Notebook repository sync with remote storage
+ */
 public class NotebookRepoSync implements NotebookRepoWithVersionControl {
   private static final Logger LOG = 
LoggerFactory.getLogger(NotebookRepoSync.class);
   private static final int maxRepoNum = 2;
@@ -45,7 +50,9 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
   private List<NotebookRepo> repos = new ArrayList<>();
   private boolean oneWaySync;
 
-  /** @param conf */
+  /**
+   * @param conf
+   */
   @SuppressWarnings("static-access")
   public NotebookRepoSync(ZeppelinConfiguration conf) throws IOException {
     init(conf);
@@ -61,12 +68,8 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     }
     String[] storageClassNames = allStorageClassNames.split(",");
     if (storageClassNames.length > getMaxRepoNum()) {
-      LOG.warn(
-          "Unsupported number {} of storage classes in 
ZEPPELIN_NOTEBOOK_STORAGE : {}\n"
-              + "first {} will be used",
-          storageClassNames.length,
-          allStorageClassNames,
-          getMaxRepoNum());
+      LOG.warn("Unsupported number {} of storage classes in 
ZEPPELIN_NOTEBOOK_STORAGE : {}\n" +
+          "first {} will be used", storageClassNames.length, 
allStorageClassNames, getMaxRepoNum());
     }
 
     for (int i = 0; i < Math.min(storageClassNames.length, getMaxRepoNum()); 
i++) {
@@ -98,35 +101,37 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
 
     NotebookRepoWithSettings repoWithSettings;
     for (NotebookRepo repo : repos) {
-      repoWithSettings =
-          NotebookRepoWithSettings.builder(repo.getClass().getSimpleName())
-              .className(repo.getClass().getName())
-              .settings(repo.getSettings(subject))
-              .build();
+      repoWithSettings = NotebookRepoWithSettings
+                           .builder(repo.getClass().getSimpleName())
+                           .className(repo.getClass().getName())
+                           .settings(repo.getSettings(subject))
+                           .build();
       reposSetting.add(repoWithSettings);
     }
 
     return reposSetting;
   }
 
-  public NotebookRepoWithSettings updateNotebookRepo(
-      String name, Map<String, String> settings, AuthenticationInfo subject) {
+  public NotebookRepoWithSettings updateNotebookRepo(String name, Map<String, 
String> settings,
+                                                     AuthenticationInfo 
subject) {
     NotebookRepoWithSettings updatedSettings = NotebookRepoWithSettings.EMPTY;
     for (NotebookRepo repo : repos) {
       if (repo.getClass().getName().equals(name)) {
         repo.updateSettings(settings, subject);
-        updatedSettings =
-            NotebookRepoWithSettings.builder(repo.getClass().getSimpleName())
-                .className(repo.getClass().getName())
-                .settings(repo.getSettings(subject))
-                .build();
+        updatedSettings = NotebookRepoWithSettings
+                            .builder(repo.getClass().getSimpleName())
+                            .className(repo.getClass().getName())
+                            .settings(repo.getSettings(subject))
+                            .build();
         break;
       }
     }
     return updatedSettings;
   }
 
-  /** Lists Notebooks from the first repository */
+  /**
+   *  Lists Notebooks from the first repository
+   */
   @Override
   public List<NoteInfo> list(AuthenticationInfo subject) throws IOException {
     return getRepo(0).list(subject);
@@ -137,7 +142,9 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     return getRepo(repoIndex).list(subject);
   }
 
-  /** Returns from Notebook from the first repository */
+  /**
+   *  Returns from Notebook from the first repository
+   */
   @Override
   public Note get(String noteId, AuthenticationInfo subject) throws 
IOException {
     return getRepo(0).get(noteId, subject);
@@ -148,14 +155,17 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     return getRepo(repoIndex).get(noteId, subject);
   }
 
-  /** Saves to all repositories */
+  /**
+   *  Saves to all repositories
+   */
   @Override
   public void save(Note note, AuthenticationInfo subject) throws IOException {
     getRepo(0).save(note, subject);
     if (getRepoCount() > 1) {
       try {
         getRepo(1).save(note, subject);
-      } catch (IOException e) {
+      }
+      catch (IOException e) {
         LOG.info(e.getMessage() + ": Failed to write to secondary storage");
       }
     }
@@ -188,12 +198,12 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     NotebookAuthorization auth = NotebookAuthorization.getInstance();
     NotebookRepo srcRepo = getRepo(sourceRepoIndex);
     NotebookRepo dstRepo = getRepo(destRepoIndex);
-    List<NoteInfo> allSrcNotes = srcRepo.list(subject);
-    List<NoteInfo> srcNotes = auth.filterByUser(allSrcNotes, subject);
-    List<NoteInfo> dstNotes = dstRepo.list(subject);
+    List <NoteInfo> allSrcNotes = srcRepo.list(subject);
+    List <NoteInfo> srcNotes = auth.filterByUser(allSrcNotes, subject);
+    List <NoteInfo> dstNotes = dstRepo.list(subject);
 
-    Map<String, List<String>> noteIds =
-        notesCheckDiff(srcNotes, srcRepo, dstNotes, dstRepo, subject);
+    Map<String, List<String>> noteIds = notesCheckDiff(srcNotes, srcRepo, 
dstNotes, dstRepo,
+        subject);
     List<String> pushNoteIds = noteIds.get(pushKey);
     List<String> pullNoteIds = noteIds.get(pullKey);
     List<String> delDstNoteIds = noteIds.get(delDstKey);
@@ -235,12 +245,8 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     sync(0, 1, subject);
   }
 
-  private void pushNotes(
-      AuthenticationInfo subject,
-      List<String> ids,
-      NotebookRepo localRepo,
-      NotebookRepo remoteRepo,
-      boolean setPermissions) {
+  private void pushNotes(AuthenticationInfo subject, List<String> ids, 
NotebookRepo localRepo,
+      NotebookRepo remoteRepo, boolean setPermissions) {
     for (String id : ids) {
       try {
         remoteRepo.save(localRepo.get(id, subject), subject);
@@ -257,7 +263,7 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     NotebookAuthorization notebookAuthorization = 
NotebookAuthorization.getInstance();
     return notebookAuthorization.getOwners(noteId).isEmpty()
         && notebookAuthorization.getReaders(noteId).isEmpty()
-        && notebookAuthorization.getRunners(noteId).isEmpty()
+            && notebookAuthorization.getRunners(noteId).isEmpty()
         && notebookAuthorization.getWriters(noteId).isEmpty();
   }
 
@@ -298,25 +304,18 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
 
   public NotebookRepo getRepo(int repoIndex) throws IOException {
     if (repoIndex < 0 || repoIndex >= getRepoCount()) {
-      throw new IOException(
-          "Requested storage index "
-              + repoIndex
-              + " isn't initialized,"
-              + " repository count is "
-              + getRepoCount());
+      throw new IOException("Requested storage index " + repoIndex
+          + " isn't initialized," + " repository count is " + getRepoCount());
     }
     return repos.get(repoIndex);
   }
 
-  private Map<String, List<String>> notesCheckDiff(
-      List<NoteInfo> sourceNotes,
-      NotebookRepo sourceRepo,
-      List<NoteInfo> destNotes,
-      NotebookRepo destRepo,
+  private Map<String, List<String>> notesCheckDiff(List<NoteInfo> sourceNotes,
+      NotebookRepo sourceRepo, List<NoteInfo> destNotes, NotebookRepo destRepo,
       AuthenticationInfo subject) {
-    List<String> pushIDs = new ArrayList<>();
-    List<String> pullIDs = new ArrayList<>();
-    List<String> delDstIDs = new ArrayList<>();
+    List <String> pushIDs = new ArrayList<>();
+    List <String> pullIDs = new ArrayList<>();
+    List <String> delDstIDs = new ArrayList<>();
 
     NoteInfo dnote;
     Date sdate, ddate;
@@ -375,7 +374,7 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     return map;
   }
 
-  private NoteInfo containsID(List<NoteInfo> notes, String id) {
+  private NoteInfo containsID(List <NoteInfo> notes, String id) {
     for (NoteInfo note : notes) {
       if (note.getId().equals(id)) {
         return note;
@@ -385,7 +384,6 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
   }
   /**
    * checks latest modification date based on Paragraph fields
-   *
    * @return -Date
    */
   private Date lastModificationDate(Note note) {
@@ -413,7 +411,7 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
   @Override
   public void close() {
     LOG.info("Closing all notebook storages");
-    for (NotebookRepo repo : repos) {
+    for (NotebookRepo repo: repos) {
       repo.close();
     }
   }
@@ -433,7 +431,7 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     return false;
   }
 
-  // checkpoint to all available storages
+  //checkpoint to all available storages
   @Override
   public Revision checkpoint(String noteId, String checkpointMsg, 
AuthenticationInfo subject)
       throws IOException {
@@ -446,24 +444,15 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     for (int i = 0; i < repoBound; i++) {
       try {
         if (isRevisionSupportedInRepo(i)) {
-          allRepoCheckpoints.add(
-              ((NotebookRepoWithVersionControl) getRepo(i))
+          allRepoCheckpoints
+              .add(((NotebookRepoWithVersionControl) getRepo(i))
                   .checkpoint(noteId, checkpointMsg, subject));
         }
       } catch (IOException e) {
-        LOG.warn(
-            "Couldn't checkpoint in {} storage with index {} for note {}",
-            getRepo(i).getClass().toString(),
-            i,
-            noteId);
-        errorMessage +=
-            "Error on storage class "
-                + getRepo(i).getClass().toString()
-                + " with index "
-                + i
-                + " : "
-                + e.getMessage()
-                + "\n";
+        LOG.warn("Couldn't checkpoint in {} storage with index {} for note {}",
+          getRepo(i).getClass().toString(), i, noteId);
+        errorMessage += "Error on storage class " + 
getRepo(i).getClass().toString() +
+          " with index " + i + " : " + e.getMessage() + "\n";
         errorCount++;
       }
     }
@@ -511,7 +500,7 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
   public List<NotebookRepoSettingsInfo> getSettings(AuthenticationInfo 
subject) {
     List<NotebookRepoSettingsInfo> repoSettings = Collections.emptyList();
     try {
-      repoSettings = getRepo(0).getSettings(subject);
+      repoSettings =  getRepo(0).getSettings(subject);
     } catch (IOException e) {
       LOG.error("Cannot get notebook repo settings", e);
     }
@@ -536,8 +525,8 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     for (int i = 0; i < repoBound; i++) {
       try {
         if (isRevisionSupportedInRepo(i)) {
-          currentNote =
-              ((NotebookRepoWithVersionControl) 
getRepo(i)).setNoteRevision(noteId, revId, subject);
+          currentNote = ((NotebookRepoWithVersionControl) getRepo(i))
+              .setNoteRevision(noteId, revId, subject);
         }
       } catch (IOException e) {
         // already logged
@@ -550,4 +539,5 @@ public class NotebookRepoSync implements 
NotebookRepoWithVersionControl {
     }
     return revisionNote;
   }
+
 }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoWithSettings.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoWithSettings.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoWithSettings.java
index cd58e7c..e5f59da 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoWithSettings.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoWithSettings.java
@@ -18,6 +18,7 @@ package org.apache.zeppelin.notebook.repo;
 
 import java.util.Collections;
 import java.util.List;
+
 import org.apache.commons.lang.StringUtils;
 
 /**
@@ -49,7 +50,9 @@ public class NotebookRepoWithSettings {
     return this.equals(EMPTY);
   }
 
-  /** Simple builder :). */
+  /**
+   * Simple builder :).
+   */
   public static class Builder {
     private final String name;
     private String className = StringUtils.EMPTY;

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoWithVersionControl.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoWithVersionControl.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoWithVersionControl.java
index e975d52..05c846e 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoWithVersionControl.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/NotebookRepoWithVersionControl.java
@@ -17,51 +17,53 @@
 
 package org.apache.zeppelin.notebook.repo;
 
-import java.io.IOException;
-import java.util.List;
 import org.apache.commons.lang.StringUtils;
 import org.apache.zeppelin.annotation.ZeppelinApi;
 import org.apache.zeppelin.notebook.Note;
+import org.apache.zeppelin.notebook.NoteInfo;
 import org.apache.zeppelin.user.AuthenticationInfo;
 
-/** Notebook repository (persistence layer) abstraction */
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Notebook repository (persistence layer) abstraction
+ */
 public interface NotebookRepoWithVersionControl extends NotebookRepo {
 
   /**
    * chekpoint (set revision) for notebook.
-   *
    * @param noteId Id of the Notebook
    * @param checkpointMsg message description of the checkpoint
    * @return Rev
    * @throws IOException
    */
-  @ZeppelinApi
-  public Revision checkpoint(String noteId, String checkpointMsg, 
AuthenticationInfo subject)
-      throws IOException;
+  @ZeppelinApi public Revision checkpoint(String noteId, String checkpointMsg,
+                                          AuthenticationInfo subject) throws 
IOException;
 
   /**
    * Get particular revision of the Notebook.
-   *
+   * 
    * @param noteId Id of the Notebook
    * @param revId revision of the Notebook
    * @return a Notebook
    * @throws IOException
    */
-  @ZeppelinApi
-  public Note get(String noteId, String revId, AuthenticationInfo subject) 
throws IOException;
+  @ZeppelinApi public Note get(String noteId, String revId, AuthenticationInfo 
subject)
+      throws IOException;
 
   /**
    * List of revisions of the given Notebook.
-   *
+   * 
    * @param noteId id of the Notebook
    * @return list of revisions
    */
-  @ZeppelinApi
-  public List<Revision> revisionHistory(String noteId, AuthenticationInfo 
subject);
+  @ZeppelinApi public List<Revision> revisionHistory(String noteId, 
AuthenticationInfo subject);
 
   /**
    * Set note to particular revision.
-   *
+   * 
    * @param noteId Id of the Notebook
    * @param revId revision of the Notebook
    * @return a Notebook
@@ -71,14 +73,16 @@ public interface NotebookRepoWithVersionControl extends 
NotebookRepo {
   public Note setNoteRevision(String noteId, String revId, AuthenticationInfo 
subject)
       throws IOException;
 
-  /** Represents the 'Revision' a point in life of the notebook */
+  /**
+   * Represents the 'Revision' a point in life of the notebook
+   */
   static class Revision {
     public static final Revision EMPTY = new Revision(StringUtils.EMPTY, 
StringUtils.EMPTY, 0);
-
+    
     public String id;
     public String message;
     public int time;
-
+    
     public Revision(String revId, String message, int time) {
       this.id = revId;
       this.message = message;
@@ -89,4 +93,5 @@ public interface NotebookRepoWithVersionControl extends 
NotebookRepo {
       return revision == null || EMPTY.equals(revision);
     }
   }
+
 }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/Instance.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/Instance.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/Instance.java
index b2174b1..2767962 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/Instance.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/Instance.java
@@ -16,7 +16,10 @@
  */
 package org.apache.zeppelin.notebook.repo.zeppelinhub.model;
 
-/** ZeppelinHub Instance structure. */
+/**
+ * ZeppelinHub Instance structure.
+ *
+ */
 public class Instance {
   public int id;
   public String name;

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/UserSessionContainer.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/UserSessionContainer.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/UserSessionContainer.java
index ee3e8b1..7f035b1 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/UserSessionContainer.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/UserSessionContainer.java
@@ -18,13 +18,17 @@ package org.apache.zeppelin.notebook.repo.zeppelinhub.model;
 
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+
 import org.apache.commons.lang.StringUtils;
 
-/** Simple and yet dummy container for zeppelinhub session. */
+/**
+ * Simple and yet dummy container for zeppelinhub session.
+ * 
+ */
 public class UserSessionContainer {
   private static class Entity {
     public final String userSession;
-
+    
     Entity(String userSession) {
       this.userSession = userSession;
     }
@@ -41,7 +45,7 @@ public class UserSessionContainer {
     }
     return entry.userSession;
   }
-
+  
   public synchronized String setSession(String principal, String userSession) {
     Entity entry = new Entity(userSession);
     sessions.put(principal, entry);

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/UserTokenContainer.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/UserTokenContainer.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/UserTokenContainer.java
index 47e5df7..b594f89 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/UserTokenContainer.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/model/UserTokenContainer.java
@@ -24,12 +24,17 @@ import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
+
 import org.apache.commons.lang.StringUtils;
 import 
org.apache.zeppelin.notebook.repo.zeppelinhub.rest.ZeppelinhubRestApiHandler;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** User token manager class. */
+/**
+ * User token manager class.
+ *
+ */
+
 public class UserTokenContainer {
   private static final Logger LOG = 
LoggerFactory.getLogger(UserTokenContainer.class);
   private static UserTokenContainer instance = null;
@@ -37,7 +42,8 @@ public class UserTokenContainer {
   private final ZeppelinhubRestApiHandler restApiClient;
   private String defaultToken;
 
-  public static UserTokenContainer init(ZeppelinhubRestApiHandler restClient, 
String defaultToken) {
+  public static UserTokenContainer init(ZeppelinhubRestApiHandler restClient, 
+      String defaultToken) {
     if (instance == null) {
       instance = new UserTokenContainer(restClient, defaultToken);
     }
@@ -52,7 +58,7 @@ public class UserTokenContainer {
   public static UserTokenContainer getInstance() {
     return instance;
   }
-
+  
   public void setUserToken(String username, String token) {
     if (StringUtils.isBlank(username) || StringUtils.isBlank(token)) {
       LOG.warn("Can't set empty user token");
@@ -60,7 +66,7 @@ public class UserTokenContainer {
     }
     userTokens.put(username, token);
   }
-
+  
   public String getUserToken(String principal) {
     if (StringUtils.isBlank(principal) || "anonymous".equals(principal)) {
       if (StringUtils.isBlank(defaultToken)) {
@@ -89,7 +95,7 @@ public class UserTokenContainer {
     }
     return token;
   }
-
+  
   public String getExistingUserToken(String principal) {
     if (StringUtils.isBlank(principal) || "anonymous".equals(principal)) {
       return StringUtils.EMPTY;
@@ -100,14 +106,15 @@ public class UserTokenContainer {
     }
     return token;
   }
-
+  
   public String removeUserToken(String username) {
     return userTokens.remove(username);
   }
-
+  
   /**
-   * Get user default instance. From now, it will be from the first instance 
from the list, But
-   * later we can think about marking a default one and return it instead :)
+   * Get user default instance.
+   * From now, it will be from the first instance from the list,
+   * But later we can think about marking a default one and return it instead 
:)
    */
   public String getDefaultZeppelinInstanceToken(String ticket) throws 
IOException {
     List<Instance> instances = getUserInstances(ticket);
@@ -116,14 +123,14 @@ public class UserTokenContainer {
     }
 
     String token = instances.get(0).token;
-    LOG.debug(
-        "The following instance has been assigned {} with token {}", 
instances.get(0).name, token);
+    LOG.debug("The following instance has been assigned {} with token {}", 
instances.get(0).name,
+        token);
     return token;
   }
-
+  
   /**
-   * Get list of user instances from Zeppelinhub. This will avoid and remove 
the needs of setting up
-   * token in zeppelin-env.sh.
+   * Get list of user instances from Zeppelinhub.
+   * This will avoid and remove the needs of setting up token in 
zeppelin-env.sh.
    */
   public List<Instance> getUserInstances(String ticket) throws IOException {
     if (StringUtils.isBlank(ticket)) {
@@ -131,11 +138,11 @@ public class UserTokenContainer {
     }
     return restApiClient.getInstances(ticket);
   }
-
+  
   public List<String> getAllTokens() {
     return new ArrayList<String>(userTokens.values());
   }
-
+  
   public Map<String, String> getAllUserTokens() {
     return new HashMap<String, String>(userTokens);
   }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/rest/HttpProxyClient.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/rest/HttpProxyClient.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/rest/HttpProxyClient.java
index 5891150..690a8b6 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/rest/HttpProxyClient.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/rest/HttpProxyClient.java
@@ -22,7 +22,9 @@ import java.net.URI;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+
 import javax.net.ssl.SSLContext;
+
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.lang.StringUtils;
 import org.apache.http.HttpHost;
@@ -54,37 +56,40 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * This is http client class for the case of proxy usage jetty-client has 
issue with https over
- * proxy for 9.2.x https://github.com/eclipse/jetty.project/issues/408
- * https://github.com/eclipse/jetty.project/issues/827
+ * This is http client class for the case of proxy usage
+ * jetty-client has issue with https over proxy for 9.2.x
+ *   https://github.com/eclipse/jetty.project/issues/408
+ *   https://github.com/eclipse/jetty.project/issues/827
+ *    
  */
+
 public class HttpProxyClient {
   private static final Logger LOG = 
LoggerFactory.getLogger(HttpProxyClient.class);
   public static final String ZEPPELIN_TOKEN_HEADER = "X-Zeppelin-Token";
-
+  
   private CloseableHttpAsyncClient client;
   private URI proxyUri;
-
+  
   public static HttpProxyClient newInstance(URI proxyUri) {
     return new HttpProxyClient(proxyUri);
   }
-
+  
   private HttpProxyClient(URI uri) {
     this.proxyUri = uri;
-
+    
     client = getAsyncProxyHttpClient(proxyUri);
     client.start();
   }
-
+  
   public URI getProxyUri() {
     return proxyUri;
   }
-
+  
   private CloseableHttpAsyncClient getAsyncProxyHttpClient(URI proxyUri) {
     LOG.info("Creating async proxy http client");
     PoolingNHttpClientConnectionManager cm = getAsyncConnectionManager();
     HttpHost proxy = new HttpHost(proxyUri.getHost(), proxyUri.getPort());
-
+    
     HttpAsyncClientBuilder clientBuilder = HttpAsyncClients.custom();
     if (cm != null) {
       clientBuilder = clientBuilder.setConnectionManager(cm);
@@ -96,7 +101,7 @@ public class HttpProxyClient {
     clientBuilder = setRedirects(clientBuilder);
     return clientBuilder.build();
   }
-
+  
   private PoolingNHttpClientConnectionManager getAsyncConnectionManager() {
     ConnectingIOReactor ioReactor = null;
     PoolingNHttpClientConnectionManager cm = null;
@@ -106,11 +111,11 @@ public class HttpProxyClient {
       SSLContext sslcontext = SSLContexts.createSystemDefault();
       X509HostnameVerifier hostnameVerifier = new 
BrowserCompatHostnameVerifier();
       @SuppressWarnings("deprecation")
-      Registry<SchemeIOSessionStrategy> sessionStrategyRegistry =
-          RegistryBuilder.<SchemeIOSessionStrategy>create()
-              .register("http", NoopIOSessionStrategy.INSTANCE)
-              .register("https", new SSLIOSessionStrategy(sslcontext, 
hostnameVerifier))
-              .build();
+      Registry<SchemeIOSessionStrategy> sessionStrategyRegistry = 
RegistryBuilder
+          .<SchemeIOSessionStrategy>create()
+          .register("http", NoopIOSessionStrategy.INSTANCE)
+          .register("https", new SSLIOSessionStrategy(sslcontext, 
hostnameVerifier))
+          .build();
 
       cm = new PoolingNHttpClientConnectionManager(ioReactor, 
sessionStrategyRegistry);
     } catch (IOReactorException e) {
@@ -119,44 +124,41 @@ public class HttpProxyClient {
     }
     return cm;
   }
-
+  
   private HttpAsyncClientBuilder setRedirects(HttpAsyncClientBuilder 
clientBuilder) {
-    clientBuilder.setRedirectStrategy(
-        new DefaultRedirectStrategy() {
-          /** Redirectable methods. */
-          private String[] REDIRECT_METHODS =
-              new String[] {
-                HttpGet.METHOD_NAME,
-                HttpPost.METHOD_NAME,
-                HttpPut.METHOD_NAME,
-                HttpDelete.METHOD_NAME,
-                HttpHead.METHOD_NAME
-              };
-
-          @Override
-          protected boolean isRedirectable(String method) {
-            for (String m : REDIRECT_METHODS) {
-              if (m.equalsIgnoreCase(method)) {
-                return true;
-              }
-            }
-            return false;
+    clientBuilder.setRedirectStrategy(new DefaultRedirectStrategy() {
+      /** Redirectable methods. */
+      private String[] REDIRECT_METHODS = new String[] { 
+        HttpGet.METHOD_NAME, HttpPost.METHOD_NAME, 
+        HttpPut.METHOD_NAME, HttpDelete.METHOD_NAME, HttpHead.METHOD_NAME 
+      };
+
+      @Override
+      protected boolean isRedirectable(String method) {
+        for (String m : REDIRECT_METHODS) {
+          if (m.equalsIgnoreCase(method)) {
+            return true;
           }
-        });
+        }
+        return false;
+      }
+    });
     return clientBuilder;
   }
-
-  public String sendToZeppelinHub(HttpRequestBase request, boolean 
withResponse)
-      throws IOException {
-    return withResponse ? sendAndGetResponse(request) : 
sendWithoutResponseBody(request);
+  
+  public String sendToZeppelinHub(HttpRequestBase request,
+      boolean withResponse) throws IOException {
+    return withResponse ?
+        sendAndGetResponse(request) : sendWithoutResponseBody(request);
   }
+  
 
   private String sendWithoutResponseBody(HttpRequestBase request) throws 
IOException {
     FutureCallback<HttpResponse> callback = getCallback(request);
     client.execute(request, callback);
     return StringUtils.EMPTY;
   }
-
+  
   private String sendAndGetResponse(HttpRequestBase request) throws 
IOException {
     String data = StringUtils.EMPTY;
     try {
@@ -167,33 +169,30 @@ public class HttpProxyClient {
           data = IOUtils.toString(responseContent, "UTF-8");
         }
       } else {
-        LOG.error(
-            "ZeppelinHub {} {} returned with status {} ",
-            request.getMethod(),
-            request.getURI(),
-            code);
+        LOG.error("ZeppelinHub {} {} returned with status {} ", 
request.getMethod(),
+            request.getURI(), code);
         throw new IOException("Cannot perform " + request.getMethod() + " 
request to ZeppelinHub");
       }
-    } catch (InterruptedException
-        | ExecutionException
-        | TimeoutException
+    } catch (InterruptedException | ExecutionException | TimeoutException
         | NullPointerException e) {
       throw new IOException(e);
     }
     return data;
   }
-
+  
   private FutureCallback<HttpResponse> getCallback(final HttpRequestBase 
request) {
     return new FutureCallback<HttpResponse>() {
 
       public void completed(final HttpResponse response) {
         request.releaseConnection();
-        LOG.info("Note {} completed with {} status", request.getMethod(), 
response.getStatusLine());
+        LOG.info("Note {} completed with {} status", request.getMethod(),
+            response.getStatusLine());
       }
 
       public void failed(final Exception ex) {
         request.releaseConnection();
-        LOG.error("Note {} failed with {} message", request.getMethod(), 
ex.getMessage());
+        LOG.error("Note {} failed with {} message", request.getMethod(),
+            ex.getMessage());
       }
 
       public void cancelled() {
@@ -202,7 +201,7 @@ public class HttpProxyClient {
       }
     };
   }
-
+  
   public void stop() {
     try {
       client.close();

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/rest/ZeppelinhubRestApiHandler.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/rest/ZeppelinhubRestApiHandler.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/rest/ZeppelinhubRestApiHandler.java
index 6d11a15..437386c 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/rest/ZeppelinhubRestApiHandler.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/rest/ZeppelinhubRestApiHandler.java
@@ -16,8 +16,6 @@
  */
 package org.apache.zeppelin.notebook.repo.zeppelinhub.rest;
 
-import com.google.gson.Gson;
-import com.google.gson.reflect.TypeToken;
 import java.io.IOException;
 import java.io.InputStream;
 import java.lang.reflect.Type;
@@ -28,6 +26,7 @@ import java.util.List;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.lang.StringUtils;
 import org.apache.http.client.methods.HttpDelete;
@@ -48,14 +47,20 @@ import org.eclipse.jetty.util.ssl.SslContextFactory;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** REST API handler. */
+import com.google.gson.Gson;
+import com.google.gson.reflect.TypeToken;
+
+/**
+ * REST API handler.
+ *
+ */
 public class ZeppelinhubRestApiHandler {
   private static final Logger LOG = 
LoggerFactory.getLogger(ZeppelinhubRestApiHandler.class);
   public static final String ZEPPELIN_TOKEN_HEADER = "X-Zeppelin-Token";
   private static final String USER_SESSION_HEADER = "X-User-Session";
   private static final String DEFAULT_API_PATH = "/api/v1/zeppelin";
   private static boolean PROXY_ON = false;
-  // TODO(xxx): possibly switch to jetty-client > 9.3.12 when adopt jvm 1.8
+  //TODO(xxx): possibly switch to jetty-client > 9.3.12 when adopt jvm 1.8
   private static HttpProxyClient proxyClient;
   private final HttpClient client;
   private String zepelinhubUrl;
@@ -76,19 +81,15 @@ public class ZeppelinhubRestApiHandler {
       LOG.error("Cannot initialize ZeppelinHub REST async client", e);
     }
   }
-
+  
   private void readProxyConf() {
-    // try reading https_proxy
-    String proxyHostString =
-        StringUtils.isBlank(System.getenv("https_proxy"))
-            ? System.getenv("HTTPS_PROXY")
-            : System.getenv("https_proxy");
+    //try reading https_proxy
+    String proxyHostString = StringUtils.isBlank(System.getenv("https_proxy")) 
?
+        System.getenv("HTTPS_PROXY") : System.getenv("https_proxy");
     if (StringUtils.isBlank(proxyHostString)) {
-      // try http_proxy if no https_proxy
-      proxyHostString =
-          StringUtils.isBlank(System.getenv("http_proxy"))
-              ? System.getenv("HTTP_PROXY")
-              : System.getenv("http_proxy");
+      //try http_proxy if no https_proxy
+      proxyHostString = StringUtils.isBlank(System.getenv("http_proxy")) ?
+          System.getenv("HTTP_PROXY") : System.getenv("http_proxy");
     }
 
     if (!StringUtils.isBlank(proxyHostString)) {
@@ -113,13 +114,12 @@ public class ZeppelinhubRestApiHandler {
     httpClient.setMaxConnectionsPerDestination(100);
 
     // Config considerations
-    // TODO(khalid): consider multi-threaded connection manager case
+    //TODO(khalid): consider multi-threaded connection manager case
     return httpClient;
   }
 
   /**
    * Fetch zeppelin instances for a given user.
-   *
    * @param ticket
    * @return
    * @throws IOException
@@ -164,7 +164,7 @@ public class ZeppelinhubRestApiHandler {
       return sendToZeppelinHub(HttpMethod.GET, url, StringUtils.EMPTY, token, 
true);
     }
   }
-
+  
   public String putWithResponseBody(String token, String url, String json) 
throws IOException {
     if (StringUtils.isBlank(url) || StringUtils.isBlank(json)) {
       LOG.error("Empty note, cannot send it to zeppelinHub");
@@ -176,7 +176,7 @@ public class ZeppelinhubRestApiHandler {
       return sendToZeppelinHub(HttpMethod.PUT, zepelinhubUrl + url, json, 
token, true);
     }
   }
-
+  
   public void put(String token, String jsonNote) throws IOException {
     if (StringUtils.isBlank(jsonNote)) {
       LOG.error("Cannot save empty note/string to ZeppelinHub");
@@ -195,16 +195,18 @@ public class ZeppelinhubRestApiHandler {
       return;
     }
     if (PROXY_ON) {
-      sendToZeppelinHubViaProxy(
-          new HttpDelete(zepelinhubUrl + argument), StringUtils.EMPTY, token, 
false);
+      sendToZeppelinHubViaProxy(new HttpDelete(zepelinhubUrl + argument), 
StringUtils.EMPTY, token,
+          false);
     } else {
-      sendToZeppelinHub(
-          HttpMethod.DELETE, zepelinhubUrl + argument, StringUtils.EMPTY, 
token, false);
+      sendToZeppelinHub(HttpMethod.DELETE, zepelinhubUrl + argument, 
StringUtils.EMPTY, token,
+          false);
     }
   }
-
-  private String sendToZeppelinHubViaProxy(
-      HttpRequestBase request, String json, String token, boolean 
withResponse) throws IOException {
+  
+  private String sendToZeppelinHubViaProxy(HttpRequestBase request, 
+                                           String json, 
+                                           String token,
+                                           boolean withResponse) throws 
IOException {
     request.setHeader(ZEPPELIN_TOKEN_HEADER, token);
     if (request.getMethod().equals(HttpPost.METHOD_NAME)) {
       HttpPost post = (HttpPost) request;
@@ -222,39 +224,36 @@ public class ZeppelinhubRestApiHandler {
     } else {
       LOG.warn("Proxy client request was submitted while not correctly 
initialized");
     }
-    return body;
+    return body; 
   }
-
-  private String sendToZeppelinHub(
-      HttpMethod method, String url, String json, String token, boolean 
withResponse)
+  
+  private String sendToZeppelinHub(HttpMethod method,
+                                   String url,
+                                   String json,
+                                   String token,
+                                   boolean withResponse)
       throws IOException {
     Request request = 
client.newRequest(url).method(method).header(ZEPPELIN_TOKEN_HEADER, token);
     if ((method.equals(HttpMethod.PUT) || method.equals(HttpMethod.POST))
         && !StringUtils.isBlank(json)) {
       request.content(new StringContentProvider(json, "UTF-8"), 
"application/json;charset=UTF-8");
     }
-    return withResponse
-        ? sendToZeppelinHub(request)
-        : sendToZeppelinHubWithoutResponseBody(request);
+    return withResponse ?
+        sendToZeppelinHub(request) : 
sendToZeppelinHubWithoutResponseBody(request);
   }
-
+  
   private String sendToZeppelinHubWithoutResponseBody(Request request) throws 
IOException {
-    request.send(
-        new Response.CompleteListener() {
-          @Override
-          public void onComplete(Result result) {
-            Request req = result.getRequest();
-            LOG.info(
-                "ZeppelinHub {} {} returned with status {}: {}",
-                req.getMethod(),
-                req.getURI(),
-                result.getResponse().getStatus(),
-                result.getResponse().getReason());
-          }
-        });
+    request.send(new Response.CompleteListener() {
+      @Override
+      public void onComplete(Result result) {
+        Request req = result.getRequest();
+        LOG.info("ZeppelinHub {} {} returned with status {}: {}", 
req.getMethod(),
+            req.getURI(), result.getResponse().getStatus(), 
result.getResponse().getReason());
+      }
+    });
     return StringUtils.EMPTY;
   }
-
+  
   private String sendToZeppelinHub(final Request request) throws IOException {
     InputStreamResponseListener listener = new InputStreamResponseListener();
     Response response;

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/security/Authentication.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/security/Authentication.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/security/Authentication.java
index e038345..38d8b50 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/security/Authentication.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/security/Authentication.java
@@ -1,7 +1,5 @@
 package org.apache.zeppelin.notebook.repo.zeppelinhub.security;
 
-import com.google.gson.Gson;
-import com.google.gson.reflect.TypeToken;
 import java.io.IOException;
 import java.io.UnsupportedEncodingException;
 import java.security.GeneralSecurityException;
@@ -9,23 +7,34 @@ import java.security.Key;
 import java.security.SecureRandom;
 import java.util.Collections;
 import java.util.Map;
+
 import javax.crypto.Cipher;
 import javax.crypto.KeyGenerator;
 import javax.crypto.SecretKey;
 import javax.crypto.spec.IvParameterSpec;
 import javax.crypto.spec.SecretKeySpec;
+
 import org.apache.commons.codec.binary.Base64;
 import org.apache.commons.httpclient.HttpClient;
 import org.apache.commons.httpclient.HttpStatus;
 import org.apache.commons.httpclient.MultiThreadedHttpConnectionManager;
 import org.apache.commons.httpclient.NameValuePair;
+import org.apache.commons.httpclient.methods.GetMethod;
 import org.apache.commons.httpclient.methods.PostMethod;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.zeppelin.conf.ZeppelinConfiguration;
+import org.apache.zeppelin.notebook.socket.Message;
+import org.apache.zeppelin.notebook.socket.Message.OP;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Authentication module. */
+import com.google.gson.Gson;
+import com.google.gson.reflect.TypeToken;
+
+/**
+ * Authentication module.
+ *
+ */
 public class Authentication implements Runnable {
   private static final Logger LOG = 
LoggerFactory.getLogger(Authentication.class);
   private String principal = "anonymous";
@@ -66,10 +75,11 @@ public class Authentication implements Runnable {
     client = new HttpClient(connectionManager);
     this.token = token;
 
-    authEnabled =
-        !conf.getBoolean("ZEPPELIN_ALLOW_ANONYMOUS", 
ZEPPELIN_CONF_ANONYMOUS_ALLOWED, true);
+    authEnabled = !conf.getBoolean("ZEPPELIN_ALLOW_ANONYMOUS",
+        ZEPPELIN_CONF_ANONYMOUS_ALLOWED, true);
 
-    userKey = conf.getString("ZEPPELINHUB_USER_KEY", ZEPPELINHUB_USER_KEY, "");
+    userKey = conf.getString("ZEPPELINHUB_USER_KEY",
+        ZEPPELINHUB_USER_KEY, "");
 
     loginEndpoint = getLoginEndpoint(conf);
   }
@@ -89,9 +99,8 @@ public class Authentication implements Runnable {
   public boolean isAuthenticated() {
     return authenticated;
   }
-
   private String getLoginEndpoint(ZeppelinConfiguration conf) {
-    int port = conf.getInt("ZEPPELIN_PORT", "zeppelin.server.port", 8080);
+    int port = conf.getInt("ZEPPELIN_PORT", "zeppelin.server.port" , 8080);
     if (port <= 0) {
       port = 8080;
     }
@@ -111,16 +120,15 @@ public class Authentication implements Runnable {
         if (isEmptyMap(authCredentials)) {
           return false;
         }
-        principal =
-            authCredentials.containsKey("principal") ? 
authCredentials.get("principal") : principal;
+        principal = authCredentials.containsKey("principal") ? 
authCredentials.get("principal")
+            : principal;
         ticket = authCredentials.containsKey("ticket") ? 
authCredentials.get("ticket") : ticket;
         roles = authCredentials.containsKey("roles") ? 
authCredentials.get("roles") : roles;
         LOG.info("Authenticated into Zeppelin as {} and roles {}", principal, 
roles);
         return true;
       } else {
-        LOG.warn(
-            "ZEPPELINHUB_USER_KEY isn't provided. Please provide your 
credentials"
-                + "for your instance in ZeppelinHub website and generate your 
key.");
+        LOG.warn("ZEPPELINHUB_USER_KEY isn't provided. Please provide your 
credentials"
+            + "for your instance in ZeppelinHub website and generate your 
key.");
       }
     }
     return false;
@@ -132,9 +140,9 @@ public class Authentication implements Runnable {
       LOG.warn("ZEPPELINHUB_USER_KEY is blank");
       return StringUtils.EMPTY;
     }
-    // use hashed token as a salt
+    //use hashed token as a salt
     String hashedToken = Integer.toString(token.hashCode());
-    return decrypt(userKey, hashedToken);
+    return decrypt(userKey, hashedToken); 
   }
 
   private String decrypt(String value, String initVector) {
@@ -172,8 +180,8 @@ public class Authentication implements Runnable {
       int code = client.executeMethod(post);
       if (code == HttpStatus.SC_OK) {
         String content = post.getResponseBodyAsString();
-        Map<String, Object> resp =
-            gson.fromJson(content, new TypeToken<Map<String, Object>>() 
{}.getType());
+        Map<String, Object> resp = gson.fromJson(content, 
+            new TypeToken<Map<String, Object>>() {}.getType());
         LOG.info("Received from Zeppelin LoginRestApi : " + content);
         return (Map<String, String>) resp.get("body");
       } else {

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/Client.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/Client.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/Client.java
index bbcd7dd..87a1a8f 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/Client.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/Client.java
@@ -22,8 +22,9 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * Client to connect Zeppelin and ZeppelinHub via websocket API. Implemented 
using singleton
- * pattern.
+ * Client to connect Zeppelin and ZeppelinHub via websocket API.
+ * Implemented using singleton pattern.
+ * 
  */
 public class Client {
   private static final Logger LOG = LoggerFactory.getLogger(Client.class);
@@ -34,8 +35,8 @@ public class Client {
   private static final int MB = 1048576;
   private static final int MAXIMUM_NOTE_SIZE = 64 * MB;
 
-  public static Client initialize(
-      String zeppelinUri, String zeppelinhubUri, String token, 
ZeppelinConfiguration conf) {
+  public static Client initialize(String zeppelinUri, String zeppelinhubUri, 
String token, 
+      ZeppelinConfiguration conf) {
     if (instance == null) {
       instance = new Client(zeppelinUri, zeppelinhubUri, token, conf);
     }
@@ -46,8 +47,8 @@ public class Client {
     return instance;
   }
 
-  private Client(
-      String zeppelinUri, String zeppelinhubUri, String token, 
ZeppelinConfiguration conf) {
+  private Client(String zeppelinUri, String zeppelinhubUri, String token,
+      ZeppelinConfiguration conf) {
     LOG.debug("Init Client");
     zeppelinhubClient = ZeppelinhubClient.initialize(zeppelinhubUri, token);
     zeppelinClient = ZeppelinClient.initialize(zeppelinUri, token, conf);

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinClient.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinClient.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinClient.java
index a338dae..0257b8c 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinClient.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinClient.java
@@ -27,6 +27,7 @@ import java.util.Timer;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
+
 import org.apache.commons.lang3.StringUtils;
 import org.apache.zeppelin.conf.ZeppelinConfiguration;
 import org.apache.zeppelin.notebook.NotebookAuthorization;
@@ -47,7 +48,11 @@ import org.eclipse.jetty.websocket.client.WebSocketClient;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Zeppelin websocket client. */
+
+/**
+ * Zeppelin websocket client.
+ *
+ */
 public class ZeppelinClient {
   private static final Logger LOG = 
LoggerFactory.getLogger(ZeppelinClient.class);
   private final URI zeppelinWebsocketUrl;
@@ -62,24 +67,22 @@ public class ZeppelinClient {
   private static final int MIN = 60;
   private static final String ORIGIN = "Origin";
 
-  private static final Set<String> actionable =
-      new HashSet<String>(
-          Arrays.asList(
-              // running events
-              "ANGULAR_OBJECT_UPDATE",
-              "PROGRESS",
-              "NOTE",
-              "PARAGRAPH",
-              "PARAGRAPH_UPDATE_OUTPUT",
-              "PARAGRAPH_APPEND_OUTPUT",
-              "PARAGRAPH_CLEAR_OUTPUT",
-              "PARAGRAPH_REMOVE",
-              // run or stop events
-              "RUN_PARAGRAPH",
-              "CANCEL_PARAGRAPH"));
+  private static final Set<String> actionable = new  
HashSet<String>(Arrays.asList(
+      // running events
+      "ANGULAR_OBJECT_UPDATE",
+      "PROGRESS",
+      "NOTE",
+      "PARAGRAPH",
+      "PARAGRAPH_UPDATE_OUTPUT",
+      "PARAGRAPH_APPEND_OUTPUT",
+      "PARAGRAPH_CLEAR_OUTPUT",
+      "PARAGRAPH_REMOVE",
+      // run or stop events
+      "RUN_PARAGRAPH",
+      "CANCEL_PARAGRAPH"));
 
-  public static ZeppelinClient initialize(
-      String zeppelinUrl, String token, ZeppelinConfiguration conf) {
+  public static ZeppelinClient initialize(String zeppelinUrl, String token, 
+      ZeppelinConfiguration conf) {
     if (instance == null) {
       instance = new ZeppelinClient(zeppelinUrl, token, conf);
     }
@@ -108,7 +111,7 @@ public class ZeppelinClient {
     client.setMaxIdleTimeout(5 * MIN * 1000);
     client.setMaxTextMessageBufferSize(Client.getMaxNoteSize());
     client.getPolicy().setMaxTextMessageSize(Client.getMaxNoteSize());
-    // TODO(khalid): other client settings
+    //TODO(khalid): other client settings
     return client;
   }
 
@@ -127,28 +130,25 @@ public class ZeppelinClient {
 
   private void addRoutines() {
     schedulerService.add(ZeppelinHeartbeat.newInstance(this), 10, 1 * MIN);
-    new Timer()
-        .schedule(
-            new java.util.TimerTask() {
-              @Override
-              public void run() {
-                int time = 0;
-                while (time < 5 * MIN) {
-                  watcherSession = openWatcherSession();
-                  if (watcherSession == null) {
-                    try {
-                      Thread.sleep(5000);
-                      time += 5;
-                    } catch (InterruptedException e) {
-                      // continue
-                    }
-                  } else {
-                    break;
-                  }
-                }
-              }
-            },
-            5000);
+    new Timer().schedule(new java.util.TimerTask() {
+      @Override
+      public void run() {
+        int time = 0;
+        while (time < 5 * MIN) {
+          watcherSession = openWatcherSession();
+          if (watcherSession == null) {
+            try {
+              Thread.sleep(5000);
+              time += 5;
+            } catch (InterruptedException e) {
+              //continue
+            }
+          } else {
+            break;
+          }
+        }
+      }
+    }, 5000);
   }
 
   public void stop() {
@@ -192,7 +192,7 @@ public class ZeppelinClient {
       return null;
     }
   }
-
+  
   private Session openWatcherSession() {
     ClientUpgradeRequest request = new ClientUpgradeRequest();
     request.setHeader(WatcherSecurityKey.HTTP_HEADER, 
WatcherSecurityKey.getKey());
@@ -218,7 +218,7 @@ public class ZeppelinClient {
     }
     noteSession.getRemote().sendStringByFuture(serialize(msg));
   }
-
+  
   public Session getZeppelinConnection(String noteId, String principal, String 
ticket) {
     if (StringUtils.isBlank(noteId)) {
       LOG.warn("Cannot get Websocket session with blanck noteId");
@@ -226,8 +226,8 @@ public class ZeppelinClient {
     }
     return getNoteSession(noteId, principal, ticket);
   }
-
-  /*
+  
+/*
   private Message zeppelinGetNoteMsg(String noteId) {
     Message getNoteMsg = new Message(Message.OP.GET_NOTE);
     HashMap<String, Object> data = new HashMap<>();
@@ -247,7 +247,7 @@ public class ZeppelinClient {
     }
     return session;
   }
-
+  
   private Session openNoteSession(String noteId, String principal, String 
ticket) {
     ClientUpgradeRequest request = new ClientUpgradeRequest();
     request.setHeader(ORIGIN, "*");
@@ -272,7 +272,7 @@ public class ZeppelinClient {
     }
     return session;
   }
-
+  
   private boolean isSessionOpen(Session session) {
     return (session != null) && (session.isOpen());
   }
@@ -289,7 +289,7 @@ public class ZeppelinClient {
 
   public void handleMsgFromZeppelin(String message, String noteId) {
     Map<String, String> meta = new HashMap<>();
-    // TODO(khalid): don't use zeppelinhubToken in this class, decouple
+    //TODO(khalid): don't use zeppelinhubToken in this class, decouple
     meta.put("noteId", noteId);
     Message zeppelinMsg = deserialize(message);
     if (zeppelinMsg == null) {
@@ -299,7 +299,7 @@ public class ZeppelinClient {
     if (!isActionable(zeppelinMsg.op)) {
       return;
     }
-
+    
     token = 
UserTokenContainer.getInstance().getUserToken(zeppelinMsg.principal);
     Client client = Client.getInstance();
     if (client == null) {
@@ -312,6 +312,7 @@ public class ZeppelinClient {
     } else {
       client.relayToZeppelinHub(hubMsg.toJson(), token);
     }
+
   }
 
   private void relayToAllZeppelinHub(ZeppelinhubMessage hubMsg, String noteId) 
{
@@ -323,7 +324,7 @@ public class ZeppelinClient {
     Client client = Client.getInstance();
     Set<String> userAndRoles;
     String token;
-    for (String user : userTokens.keySet()) {
+    for (String user: userTokens.keySet()) {
       userAndRoles = noteAuth.getRoles(user);
       userAndRoles.add(user);
       if (noteAuth.isReader(noteId, userAndRoles)) {
@@ -340,7 +341,7 @@ public class ZeppelinClient {
     }
     return actionable.contains(action.name());
   }
-
+  
   public void removeNoteConnection(String noteId) {
     if (StringUtils.isBlank(noteId)) {
       LOG.error("Cannot remove session for empty noteId");
@@ -355,14 +356,14 @@ public class ZeppelinClient {
     }
     LOG.info("Removed note websocket connection for note {}", noteId);
   }
-
+  
   private void removeAllConnections() {
     if (watcherSession != null && watcherSession.isOpen()) {
       watcherSession.close();
     }
 
     Session noteSession = null;
-    for (Map.Entry<String, Session> note : notesConnection.entrySet()) {
+    for (Map.Entry<String, Session> note: notesConnection.entrySet()) {
       noteSession = note.getValue();
       if (isSessionOpen(noteSession)) {
         noteSession.close();
@@ -378,8 +379,10 @@ public class ZeppelinClient {
     }
     watcherSession.getRemote().sendStringByFuture(serialize(new 
Message(OP.PING)));
   }
-
-  /** Only used in test. */
+  
+  /**
+   * Only used in test.
+   */
   public int countConnectedNotes() {
     return notesConnection.size();
   }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinhubClient.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinhubClient.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinhubClient.java
index 098aecb..4c03a66 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinhubClient.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinhubClient.java
@@ -16,12 +16,7 @@
  */
 package org.apache.zeppelin.notebook.repo.zeppelinhub.websocket;
 
-import com.amazonaws.util.json.JSONArray;
-import com.amazonaws.util.json.JSONException;
-import com.amazonaws.util.json.JSONObject;
-import com.google.common.collect.Lists;
-import com.google.gson.Gson;
-import com.google.gson.reflect.TypeToken;
+
 import java.io.IOException;
 import java.net.HttpCookie;
 import java.net.URI;
@@ -30,6 +25,7 @@ import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
+
 import org.apache.commons.lang.StringUtils;
 import 
org.apache.zeppelin.notebook.repo.zeppelinhub.websocket.listener.ZeppelinhubWebsocket;
 import 
org.apache.zeppelin.notebook.repo.zeppelinhub.websocket.protocol.ZeppelinHubOp;
@@ -48,7 +44,16 @@ import org.eclipse.jetty.websocket.client.WebSocketClient;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Manage a zeppelinhub websocket connection. */
+import com.amazonaws.util.json.JSONArray;
+import com.amazonaws.util.json.JSONException;
+import com.amazonaws.util.json.JSONObject;
+import com.google.common.collect.Lists;
+import com.google.gson.Gson;
+import com.google.gson.reflect.TypeToken;
+
+/**
+ * Manage a zeppelinhub websocket connection.
+ */
 public class ZeppelinhubClient {
   private static final Logger LOG = 
LoggerFactory.getLogger(ZeppelinhubClient.class);
 
@@ -60,9 +65,9 @@ public class ZeppelinhubClient {
   private static final long CONNECTION_IDLE_TIME = 
TimeUnit.SECONDS.toMillis(30);
   private static ZeppelinhubClient instance = null;
   private static Gson gson;
-
+  
   private SchedulerService schedulerService;
-  private Map<String, ZeppelinhubSession> sessionMap =
+  private Map<String, ZeppelinhubSession> sessionMap = 
       new ConcurrentHashMap<String, ZeppelinhubSession>();
 
   public static ZeppelinhubClient initialize(String zeppelinhubUrl, String 
token) {
@@ -93,8 +98,10 @@ public class ZeppelinhubClient {
       LOG.error("Cannot connect to zeppelinhub via websocket", e);
     }
   }
-
-  public void initUser(String token) {}
+  
+  public void initUser(String token) {
+    
+  }
 
   public void stop() {
     LOG.info("Stopping Zeppelinhub websocket client");
@@ -113,7 +120,7 @@ public class ZeppelinhubClient {
   public String getToken() {
     return this.zeppelinhubToken;
   }
-
+  
   public void send(String msg, String token) {
     ZeppelinhubSession zeppelinhubSession = getSession(token);
     if (!isConnectedToZeppelinhub(zeppelinhubSession)) {
@@ -126,7 +133,7 @@ public class ZeppelinhubClient {
     }
     zeppelinhubSession.sendByFuture(msg);
   }
-
+  
   private boolean isConnectedToZeppelinhub(ZeppelinhubSession 
zeppelinhubSession) {
     return (zeppelinhubSession != null && zeppelinhubSession.isSessionOpen());
   }
@@ -173,7 +180,7 @@ public class ZeppelinhubClient {
     request.setCookies(Lists.newArrayList(new HttpCookie(TOKEN_HEADER, 
token)));
     return request;
   }
-
+  
   private WebSocketClient createNewWebsocketClient() {
     SslContextFactory sslContextFactory = new SslContextFactory();
     WebSocketClient client = new WebSocketClient(sslContextFactory);
@@ -182,7 +189,7 @@ public class ZeppelinhubClient {
     client.setMaxIdleTimeout(CONNECTION_IDLE_TIME);
     return client;
   }
-
+  
   private void addRoutines() {
     schedulerService.add(ZeppelinHubHeartbeat.newInstance(this), 10, 23);
   }
@@ -262,9 +269,8 @@ public class ZeppelinhubClient {
           LOG.warn("Wrong \"paragraph\" format for RUN_NOTEBOOK");
           continue;
         }
-        zeppelinMsg.data =
-            gson.fromJson(
-                paragraphs.getString(i), new TypeToken<Map<String, Object>>() 
{}.getType());
+        zeppelinMsg.data = gson.fromJson(paragraphs.getString(i), 
+            new TypeToken<Map<String, Object>>(){}.getType());
         zeppelinMsg.principal = principal;
         zeppelinMsg.ticket = TicketContainer.instance.getTicket(principal);
         client.relayToZeppelin(zeppelinMsg, noteId);
@@ -276,4 +282,5 @@ public class ZeppelinhubClient {
     }
     return true;
   }
+
 }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/WatcherWebsocket.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/WatcherWebsocket.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/WatcherWebsocket.java
index 72b172e..43adf4a 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/WatcherWebsocket.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/WatcherWebsocket.java
@@ -27,18 +27,22 @@ import org.eclipse.jetty.websocket.api.WebSocketListener;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Zeppelin Watcher that will forward user note to ZeppelinHub. */
+/**
+ * Zeppelin Watcher that will forward user note to ZeppelinHub.
+ *
+ */
 public class WatcherWebsocket implements WebSocketListener {
   private static final Logger LOG = 
LoggerFactory.getLogger(ZeppelinWebsocket.class);
   private static final String watcherPrincipal = "watcher";
   public Session connection;
-
+  
   public static WatcherWebsocket createInstace() {
     return new WatcherWebsocket();
   }
-
+  
   @Override
-  public void onWebSocketBinary(byte[] payload, int offset, int len) {}
+  public void onWebSocketBinary(byte[] payload, int offset, int len) {
+  }
 
   @Override
   public void onWebSocketClose(int code, String reason) {
@@ -75,4 +79,5 @@ public class WatcherWebsocket implements WebSocketListener {
       LOG.error("Failed to send message to ZeppelinHub: ", e);
     }
   }
+
 }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinWebsocket.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinWebsocket.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinWebsocket.java
index fb078ae..fa6ade8 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinWebsocket.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinWebsocket.java
@@ -22,7 +22,10 @@ import org.eclipse.jetty.websocket.api.WebSocketListener;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Zeppelin websocket listener class. */
+/**
+ * Zeppelin websocket listener class.
+ *
+ */
 public class ZeppelinWebsocket implements WebSocketListener {
   private static final Logger LOG = 
LoggerFactory.getLogger(ZeppelinWebsocket.class);
   public Session connection;
@@ -33,7 +36,9 @@ public class ZeppelinWebsocket implements WebSocketListener {
   }
 
   @Override
-  public void onWebSocketBinary(byte[] arg0, int arg1, int arg2) {}
+  public void onWebSocketBinary(byte[] arg0, int arg1, int arg2) {
+
+  }
 
   @Override
   public void onWebSocketClose(int code, String message) {
@@ -66,4 +71,5 @@ public class ZeppelinWebsocket implements WebSocketListener {
       LOG.error("Failed to send message to ZeppelinHub: {}", e.toString());
     }
   }
+
 }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinhubWebsocket.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinhubWebsocket.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinhubWebsocket.java
index 713be82..216c307 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinhubWebsocket.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinhubWebsocket.java
@@ -23,12 +23,14 @@ import org.eclipse.jetty.websocket.api.WebSocketListener;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Zeppelinhub websocket handler. */
+/**
+ * Zeppelinhub websocket handler.
+ */
 public class ZeppelinhubWebsocket implements WebSocketListener {
   private Logger LOG = LoggerFactory.getLogger(ZeppelinhubWebsocket.class);
   private Session zeppelinHubSession;
   private final String token;
-
+  
   private ZeppelinhubWebsocket(String token) {
     this.token = token;
   }
@@ -36,7 +38,7 @@ public class ZeppelinhubWebsocket implements 
WebSocketListener {
   public static ZeppelinhubWebsocket newInstance(String token) {
     return new ZeppelinhubWebsocket(token);
   }
-
+  
   @Override
   public void onWebSocketBinary(byte[] payload, int offset, int len) {}
 
@@ -71,7 +73,7 @@ public class ZeppelinhubWebsocket implements 
WebSocketListener {
   private boolean isSessionOpen() {
     return ((zeppelinHubSession != null) && (zeppelinHubSession.isOpen())) ? 
true : false;
   }
-
+  
   private void send(String msg) {
     if (isSessionOpen()) {
       zeppelinHubSession.getRemote().sendStringByFuture(msg);

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/protocol/ZeppelinHubOp.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/protocol/ZeppelinHubOp.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/protocol/ZeppelinHubOp.java
index b5dd1d5..80d5f06 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/protocol/ZeppelinHubOp.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/protocol/ZeppelinHubOp.java
@@ -16,7 +16,9 @@
  */
 package org.apache.zeppelin.notebook.repo.zeppelinhub.websocket.protocol;
 
-/** Zeppelinhub Op. */
+/**
+ * Zeppelinhub Op.
+ */
 public enum ZeppelinHubOp {
   LIVE,
   DEAD,

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/protocol/ZeppelinhubMessage.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/protocol/ZeppelinhubMessage.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/protocol/ZeppelinhubMessage.java
index de7e7b6..4f7c652 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/protocol/ZeppelinhubMessage.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/protocol/ZeppelinhubMessage.java
@@ -16,10 +16,8 @@
  */
 package org.apache.zeppelin.notebook.repo.zeppelinhub.websocket.protocol;
 
-import com.google.common.collect.Maps;
-import com.google.gson.Gson;
-import com.google.gson.JsonSyntaxException;
 import java.util.Map;
+
 import org.apache.commons.lang.StringUtils;
 import org.apache.zeppelin.common.JsonSerializable;
 import org.apache.zeppelin.notebook.repo.zeppelinhub.websocket.Client;
@@ -28,7 +26,14 @@ import org.apache.zeppelin.notebook.socket.Message.OP;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Zeppelinhub message class. */
+import com.google.common.collect.Maps;
+import com.google.gson.Gson;
+import com.google.gson.JsonSyntaxException;
+
+/**
+ * Zeppelinhub message class.
+ *
+ */
 public class ZeppelinhubMessage implements JsonSerializable {
   private static final Gson gson = new Gson();
   private static final Logger LOG = LoggerFactory.getLogger(Client.class);
@@ -37,18 +42,18 @@ public class ZeppelinhubMessage implements JsonSerializable 
{
   public Object op;
   public Object data;
   public Map<String, String> meta = Maps.newHashMap();
-
+  
   private ZeppelinhubMessage() {
     this.op = OP.LIST_NOTES;
     this.data = null;
   }
-
+  
   private ZeppelinhubMessage(Object op, Object data, Map<String, String> meta) 
{
     this.op = op;
     this.data = data;
     this.meta = meta;
   }
-
+  
   public static ZeppelinhubMessage newMessage(Object op, Object data, 
Map<String, String> meta) {
     return new ZeppelinhubMessage(op, data, meta);
   }
@@ -77,4 +82,5 @@ public class ZeppelinhubMessage implements JsonSerializable {
     }
     return msg;
   }
+  
 }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/SchedulerService.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/SchedulerService.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/SchedulerService.java
index 1958bf0..024a3c0 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/SchedulerService.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/SchedulerService.java
@@ -20,7 +20,10 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
-/** Creates a thread pool that can schedule zeppelinhub commands. */
+/**
+ * Creates a thread pool that can schedule zeppelinhub commands.
+ *
+ */
 public class SchedulerService {
 
   private final ScheduledExecutorService pool;
@@ -55,4 +58,5 @@ public class SchedulerService {
   public void close() {
     pool.shutdown();
   }
+
 }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/ZeppelinHeartbeat.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/ZeppelinHeartbeat.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/ZeppelinHeartbeat.java
index d1cfed9..11cfa45 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/ZeppelinHeartbeat.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/ZeppelinHeartbeat.java
@@ -20,15 +20,18 @@ import 
org.apache.zeppelin.notebook.repo.zeppelinhub.websocket.ZeppelinClient;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Routine that sends PING to all connected Zeppelin ws connections. */
+/**
+ * Routine that sends PING to all connected Zeppelin ws connections.
+ *
+ */
 public class ZeppelinHeartbeat implements Runnable {
   private static final Logger LOG = 
LoggerFactory.getLogger(ZeppelinHubHeartbeat.class);
   private ZeppelinClient client;
-
+  
   public static ZeppelinHeartbeat newInstance(ZeppelinClient client) {
     return new ZeppelinHeartbeat(client);
   }
-
+  
   private ZeppelinHeartbeat(ZeppelinClient client) {
     this.client = client;
   }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/ZeppelinHubHeartbeat.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/ZeppelinHubHeartbeat.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/ZeppelinHubHeartbeat.java
index 9a7e7a8..2282147 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/ZeppelinHubHeartbeat.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/ZeppelinHubHeartbeat.java
@@ -22,24 +22,27 @@ import 
org.apache.zeppelin.notebook.repo.zeppelinhub.websocket.utils.Zeppelinhub
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Routine that send PING event to zeppelinhub. */
+/**
+ * Routine that send PING event to zeppelinhub.
+ *
+ */
 public class ZeppelinHubHeartbeat implements Runnable {
   private static final Logger LOG = 
LoggerFactory.getLogger(ZeppelinHubHeartbeat.class);
   private ZeppelinhubClient client;
-
+  
   public static ZeppelinHubHeartbeat newInstance(ZeppelinhubClient client) {
     return new ZeppelinHubHeartbeat(client);
   }
-
+  
   private ZeppelinHubHeartbeat(ZeppelinhubClient client) {
     this.client = client;
   }
-
+  
   @Override
   public void run() {
     LOG.debug("Sending PING to zeppelinhub token");
-    for (String token : UserTokenContainer.getInstance().getAllTokens()) {
+    for (String token: UserTokenContainer.getInstance().getAllTokens()) {
       client.send(ZeppelinhubUtils.pingMessage(token), token);
     }
-  }
+  }  
 }

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/session/ZeppelinhubSession.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/session/ZeppelinhubSession.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/session/ZeppelinhubSession.java
index 9cb7249..86cd4ad 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/session/ZeppelinhubSession.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/session/ZeppelinhubSession.java
@@ -21,33 +21,35 @@ import org.eclipse.jetty.websocket.api.Session;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Zeppelinhub session. */
+/**
+ * Zeppelinhub session.
+ */
 public class ZeppelinhubSession {
   private static final Logger LOG = 
LoggerFactory.getLogger(ZeppelinhubSession.class);
   private Session session;
   private final String token;
-
+  
   public static final ZeppelinhubSession EMPTY = new ZeppelinhubSession(null, 
StringUtils.EMPTY);
-
+  
   public static ZeppelinhubSession createInstance(Session session, String 
token) {
     return new ZeppelinhubSession(session, token);
   }
-
+  
   private ZeppelinhubSession(Session session, String token) {
     this.session = session;
     this.token = token;
   }
-
+  
   public boolean isSessionOpen() {
     return ((session != null) && (session.isOpen()));
   }
-
+  
   public void close() {
     if (isSessionOpen()) {
       session.close();
     }
   }
-
+  
   public void sendByFuture(String msg) {
     if (StringUtils.isBlank(msg)) {
       LOG.error("Cannot send event to Zeppelinhub, msg is empty");

http://git-wip-us.apache.org/repos/asf/zeppelin/blob/0d746fa2/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/utils/ZeppelinhubUtils.java
----------------------------------------------------------------------
diff --git 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/utils/ZeppelinhubUtils.java
 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/utils/ZeppelinhubUtils.java
index b81780b..50da343 100644
--- 
a/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/utils/ZeppelinhubUtils.java
+++ 
b/zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/utils/ZeppelinhubUtils.java
@@ -17,6 +17,7 @@
 package org.apache.zeppelin.notebook.repo.zeppelinhub.websocket.utils;
 
 import java.util.HashMap;
+
 import org.apache.commons.lang.StringUtils;
 import org.apache.zeppelin.notebook.repo.zeppelinhub.model.UserTokenContainer;
 import 
org.apache.zeppelin.notebook.repo.zeppelinhub.websocket.ZeppelinhubClient;
@@ -26,7 +27,10 @@ import org.apache.zeppelin.notebook.socket.Message;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-/** Helper class. */
+/**
+ * Helper class.
+ *
+ */
 public class ZeppelinhubUtils {
   private static final Logger LOG = 
LoggerFactory.getLogger(ZeppelinhubUtils.class);
 
@@ -37,10 +41,11 @@ public class ZeppelinhubUtils {
     }
     HashMap<String, Object> data = new HashMap<>();
     data.put("token", token);
-    return ZeppelinhubMessage.newMessage(ZeppelinHubOp.LIVE, data, new 
HashMap<String, String>())
-        .toJson();
+    return ZeppelinhubMessage
+             .newMessage(ZeppelinHubOp.LIVE, data, new HashMap<String, 
String>())
+             .toJson();
   }
-
+  
   public static String deadMessage(String token) {
     if (StringUtils.isBlank(token)) {
       LOG.error("Cannot create Dead message: token is null or empty");
@@ -48,10 +53,11 @@ public class ZeppelinhubUtils {
     }
     HashMap<String, Object> data = new HashMap<>();
     data.put("token", token);
-    return ZeppelinhubMessage.newMessage(ZeppelinHubOp.DEAD, data, new 
HashMap<String, String>())
-        .toJson();
+    return ZeppelinhubMessage
+             .newMessage(ZeppelinHubOp.DEAD, data, new HashMap<String, 
String>())
+             .toJson();
   }
-
+  
   public static String pingMessage(String token) {
     if (StringUtils.isBlank(token)) {
       LOG.error("Cannot create Ping message: token is null or empty");
@@ -59,8 +65,9 @@ public class ZeppelinhubUtils {
     }
     HashMap<String, Object> data = new HashMap<>();
     data.put("token", token);
-    return ZeppelinhubMessage.newMessage(ZeppelinHubOp.PING, data, new 
HashMap<String, String>())
-        .toJson();
+    return ZeppelinhubMessage
+             .newMessage(ZeppelinHubOp.PING, data, new HashMap<String, 
String>())
+             .toJson();
   }
 
   public static ZeppelinHubOp toZeppelinHubOp(String text) {
@@ -74,7 +81,7 @@ public class ZeppelinhubUtils {
   }
 
   public static boolean isZeppelinHubOp(String text) {
-    return (toZeppelinHubOp(text) != null);
+    return (toZeppelinHubOp(text) != null); 
   }
 
   public static Message.OP toZeppelinOp(String text) {
@@ -88,31 +95,33 @@ public class ZeppelinhubUtils {
   }
 
   public static boolean isZeppelinOp(String text) {
-    return (toZeppelinOp(text) != null);
+    return (toZeppelinOp(text) != null); 
   }
-
+  
   public static void userLoginRoutine(String username) {
     LOG.debug("Executing user login routine");
     String token = UserTokenContainer.getInstance().getUserToken(username);
     UserTokenContainer.getInstance().setUserToken(username, token);
     String msg = ZeppelinhubUtils.liveMessage(token);
-    ZeppelinhubClient.getInstance().send(msg, token);
+    ZeppelinhubClient.getInstance()
+        .send(msg, token);
   }
-
+  
   public static void userLogoutRoutine(String username) {
     LOG.debug("Executing user logout routine");
     String token = UserTokenContainer.getInstance().removeUserToken(username);
     String msg = ZeppelinhubUtils.deadMessage(token);
-    ZeppelinhubClient.getInstance().send(msg, token);
+    ZeppelinhubClient.getInstance()
+        .send(msg, token);
     ZeppelinhubClient.getInstance().removeSession(token);
   }
-
-  public static void userSwitchTokenRoutine(
-      String username, String originToken, String targetToken) {
+  
+  public static void userSwitchTokenRoutine(String username, String 
originToken,
+      String targetToken) {
     String offMsg = ZeppelinhubUtils.deadMessage(originToken);
     ZeppelinhubClient.getInstance().send(offMsg, originToken);
     ZeppelinhubClient.getInstance().removeSession(originToken);
-
+    
     String onMsg = ZeppelinhubUtils.liveMessage(targetToken);
     ZeppelinhubClient.getInstance().send(onMsg, targetToken);
   }

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