private static FileStatus convertStatus(@Nullable ContentRevision beforeRevision, @Nullable ContentRevision afterRevision) {
    if (beforeRevision == null) return FileStatus.ADDED;
    if (afterRevision == null) return FileStatus.DELETED;
    return FileStatus.MODIFIED;
  }
private static FileStatus convertStatus(@Nullable ContentRevision beforeRevision, @Nullable ContentRevision afterRevision)