ReferenceQueue<K> getKeyReferenceQueueForTesting() {
      throw new AssertionError();
    }

    /** Unsafely extracts the value reference queue used by this segment. */
    ReferenceQueue<V> getValueReferenceQueueForTesting() {
      throw new AssertionError();
    }

    /** Unsafely extracts the weak value reference inside of the given {@code entry}. */