Just a backup. InitAuth class is a working implementation for retrieving auth code, but currently I wana separate it out to achieve better modularity.
Transform InitAuth class into User class. And it seems like if the obtained crediential contains refresh token, it will automatically refresh itself when its access token is expired.
Working on storing the initially obtained google credential and recreating credential from StoredCredential object(serializable obj read from file).
LaunchApp.java: added JVM shutdown hook draft.
ConfigManager.java: preliminary serializable class that will be used to hold configurations
FileManager.java: Create necessary in case user stored credential do not exist.
User.java: move the part that stores credential into shutdown hook in persistance package.
ShutDown.java: this class extends the Thread class and will be called when JVM is about to shutdown to save all necessary configurations, sync progress (for resumable uploads), etc.
User.java: added "private Drive service" so that FileManager can manage files under each user.