output: #fixed code
                                  private void sendPushNotification(DashBoard dashBoard, Notification notification, int dashId, int deviceId) {
          Device device = dashBoard.getDeviceById(deviceId);
          final String dashName = dashBoard.name == null ? "" : dashBoard.name;
          final String deviceName = ((device == null || device.name == null) ? "device" : device.name);
          String message = "Your " + deviceName + " went offline. \"" + dashName + "\" project is disconnected.";
          notification.push(gcmWrapper,
                  message,
                  dashId
          );
      }
input: #vulnerable code 
                                  private void sendPushNotification(DashBoard dashBoard, Notification notification, int dashId, int deviceId) {
          Device device = dashBoard.getDeviceById(deviceId);
          final String dashName = dashBoard.name == null ? "" : dashBoard.name;
          final String deviceName = device.name == null ? "device" : device.name;
          String message = "Your " + deviceName + " went offline. \"" + dashName + "\" project is disconnected.";
          notification.push(gcmWrapper,
                  message,
                  dashId
          );
      } 
                              #location 4 
                              #vulnerability type NULL_DEREFERENCE