code: void updateJournalMetrics() {
      if (metrics == null) {
        return;
      }
      int failedJournals = 0;
      for(JournalAndStream jas : journals) {
        if(jas.isDisabled()) {
          failedJournals++;
        }
      }
      metrics.journalsFailed.set(failedJournals);
    }
docs: Get the number of available journals.