code: public void initFromBackup(InputStream is) throws IOException {
      int count = 0;
      try (GzipCompressorInputStream gzIn = new GzipCompressorInputStream(is);
           JournalEntryStreamReader reader = new JournalEntryStreamReader(gzIn)) {
        List<Master> masters = mRegistry.getServers();
        JournalEntry entry;
        Map<String, Master> mastersByName = Maps.uniqueIndex(masters, Master::getName);
        while ((entry = reader.readEntry()) != null) {
          String masterName = JournalEntryAssociation.getMasterForEntry(entry);
          Master master = mastersByName.get(masterName);
          try {
            master.processJournalEntry(entry);
          } catch (Throwable t) {
            JournalUtils.handleJournalReplayFailure(
                LOG, t, "Failed to process journal entry %s when init from backup", entry);
          }
          try (JournalContext jc = master.createJournalContext()) {
            jc.append(entry);
            count++;
          }
        }
      }
      LOG.info("Restored {} entries from backup", count);
    }
docs: Restores master state from the specified backup.
  
  @param is an input stream to read from the backup