code: private void maybeClose(@Nullable ArrayList<Entry<K, V>> oldEntries) {
      if (oldEntries != null) {
        for (Entry<K, V> oldEntry : oldEntries) {
          CloseableReference.closeSafely(referenceToClose(oldEntry));
        }
      }
    }
docs: Notifies the client that the cache no longer tracks the given items.
  
  <p> This method invokes the external {@link CloseableReference#close} method,
  so it must not be called while holding the <code>this</code> lock.