code: private void saveBuckets() {
          if (lastModifiedOn > lastSavedOn) {
              System.out.println("Persisting current rates to: " + savedRates); //$NON-NLS-1$
              Properties props = new Properties();
              for (Entry<String, RateLimiterBucket> entry : buckets.entrySet()) {
                  String value = entry.getValue().getCount() + "|" + entry.getValue().getLast(); //$NON-NLS-1$
                  props.setProperty(entry.getKey(), value);
              }
              try (FileWriter writer = new FileWriter(savedRates)) {
                  props.store(writer, "All apiman rate limits"); //$NON-NLS-1$
              } catch (IOException e) {
                  e.printStackTrace();
              }
              lastSavedOn = System.currentTimeMillis();
          }
      }
docs: Saves the current list of buckets into a file.