docs: private boolean cancelAndCleanUpIfEmpty(Integer second, Map<Object, ScheduledEntry<K, V>> entries, Object key,
                                              ScheduledEntry<K, V> entryToRemove) {
          ScheduledEntry<K, V> entry = entries.get(key);
          if (entry == null || !entry.equals(entryToRemove)) {
              return false;
          }
          entries.remove(key);
          cleanUpScheduledFuturesIfEmpty(second, entries);
          return true;
      }