docs: private void restoreBackup() {
  
          if (incBackup) {
              restoreBackupIncremental();
  
              return;
          }
  
          // in case data file cannot be deleted, reset it
          DataFileCache.deleteOrResetFreePos(database, fileName + ".data");
  
          try {
              FileArchiver.unarchive(fileName + ".backup", fileName + ".data",
                                     database.getFileAccess(),
                                     FileArchiver.COMPRESSION_ZIP);
          } catch (Exception e) {
              throw Error.error(ErrorCode.FILE_IO_ERROR,
                                ErrorCode.M_Message_Pair, new Object[] {
                  fileName + ".backup", e.toString()
              });
          }
      }