public V remove(Object key) {
    Timestamped<V> stamped = cachingHashMap.remove(key);
    if (stamped != null) {
      V value = stamped.getValue();
      // `key` was in the cache, so it's a K.
      // (Or it's a weird case like a LinkedList in a Cache<ArrayList, ...>, but *shrug*.)
      @SuppressWarnings("unchecked")
      K castKey = (K) key;

      if (!isExpired(stamped)) {