@Override
  public boolean shouldBackup(File file) {
    return backupStrategy.shouldBackup(file);
  }
Wrap a {@link BackupStrategy} to fit the {@link BackupStrategy2} interface, and perform like
a {@link BackupStrategy} with the old logic before v1.9.0.
xlog/src/main/java/com/elvishew/xlog/internal/printer/file/backup/BackupStrategyWrapper.java