class WindowingKey implements Serializable {

	public WindowingKey(User user, DeviceId deviceId, CollectionId collectionId, SyncKey syncKey) {
		Preconditions.checkArgument(user != null);
		Preconditions.checkArgument(deviceId != null);
		Preconditions.checkArgument(collectionId != null);
		Preconditions.checkArgument(syncKey != null);
		this.user = user;
		this.deviceId = deviceId;
		this.collectionId = collectionId;
		this.syncKey = syncKey;
	}

	public  WindowingKey(User user, DeviceId deviceId, CollectionId collectionId, SyncKey syncKey);

}