docs: protected void sweepCache() {
          for (Iterator keyIterator = keySet().iterator(); keyIterator.hasNext(); ) {
              Object key = keyIterator.next();
              ValueWrapper valueWrapper = (ValueWrapper) super.get(key);
              long creationTime = valueWrapper.getCreationTime();
              long cacheInterval = valueWrapper.getCacheInterval();
              long currentTime = System.currentTimeMillis();
              if (cacheInterval >= 0 && creationTime + cacheInterval < currentTime) {
                  remove(key);
              }
          }
      }