[Demonstration 1]

[Buggy Method]
@RequestMapping(method = RequestMethod.POST, path = "logout", consumes = MediaType.ALL_VALUE)
public ResponseEntity<?> logout(HttpSession httpSession) {
    if (httpSession == null || httpSession.isNew()) {
        return ResponseEntity.badRequest().body(new RestJsonAnswer("Is not sign in yet", "You can not logout if you are not singed in"));
    }
    httpSession.invalidate();
    return ResponseEntity.ok().build();
}

[Buggy Hunk]
return ResponseEntity.badRequest()

[Patch]
return ResponseEntity.status(HttpStatus.UNAUTHORIZED)

[Demonstration 2]

[Buggy Method]
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setHasOptionsMenu(true);
    mStationDB = new StationDB(this.getContext());
    // adding userID to obtain their specific data
    SharedPreferences mSharedPreferences = this.getActivity().getSharedPreferences(getString(R.string.PREFS_FILE), Context.MODE_PRIVATE);
    String userIdSharePref = mSharedPreferences.getString("@string/userID", null);
    Log.d(TAG, userIdSharePref);
    StringBuilder listURLBuilder = new StringBuilder();
    listURLBuilder.append("&userID=");
    listURLBuilder.append(userIdSharePref);
    listURL += listURLBuilder;
}

[Buggy Hunk]
String userIdSharePref = mSharedPreferences.getString("@string/userID", null);

[Patch]
String userIdSharePref = mSharedPreferences.getString(getString(R.string.PREFS_USER_ID), null);

[Demonstration 3]

[Buggy Method]
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ButterKnife.bind(this);
    mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    mUId = mSharedPreferences.getString(Constants.KEY_UID, null);
    mUserRef = new Firebase(Constants.FIREBASE_URL_USERS).child(mUId);
    mMakePlansButton.setOnClickListener(this);
    mViewEventsButton.setOnClickListener(this);
    Typeface myCustomFont = Typeface.createFromAsset(getAssets(), "fonts/bario.ttf");
    mTextView.setTypeface(myCustomFont);
    setTitle(null);
    setSupportActionBar(topToolBar);
    mSavedEventRef = new Firebase(Constants.FIREBASE_URL_EVENT);
    mFirebaseRef = new Firebase(Constants.FIREBASE_URL);
    mSavedEventRefListener = mSavedEventRef.addValueEventListener(new ValueEventListener() {

        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.getValue() != null) {
                String events = dataSnapshot.getValue().toString();
                Log.d("Events added", events);
            }
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {
        }
    });
    mUserRefListener = mUserRef.addValueEventListener(new ValueEventListener() {

        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            User user = dataSnapshot.getValue(User.class);
            mWelcomeTextView.setText("Welcome, " + user.getName() + ", to");
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {
            Log.d(TAG, "Read failed");
        }
    });
}

[Buggy Hunk]
mWelcomeTextView.setText("Welcome, " + user.getName() + ", to");

[Patch]
mWelcomeTextView.setText(user.getName());