Detect conflict when uploading document to Google Drive
问题 My Android app updates a Google Drive document. The file can be modified also elsewhere (e.g. through Drive web interface), so there may be a conflict on file upload. However, this should rarely happen. That's why I don't want my app to first query the revision history (since this is in most cases unnecessary) and only after that, update the file. How can I detect that there is a conflict when updating the file? My investigation so far reveals that getHeadRevisionId() returns null although