docs: public void purge() {
          long time = System.currentTimeMillis();
          if (time - latestWriteTime > expireMillis) {
              // Everything in the map is expired, clear all at once
              map.clear();
          } else {
              // Iterate and remove until the first non-expired token
              Iterator<Value> values = map.values().iterator();
              while (values.hasNext()) {
                  if (time >= values.next().expire) {
                      values.remove();
                  } else {
                      break;
                  }
              }
          }
      }