Log.d(TAG,"mySyncedState last modified: "+mSyncedState.getLocalLastModified()+" <=> mFile last modified: "+mFile.lastModified()+": So return sync_conflict");
(!checkEtag||mSyncedState.getLastETAG().isEmpty())?null:mSyncedState.getLastETAG(),//If not null, This can cause error 412; that means remote file has change