}

  @CanIgnoreReturnValue
  @Override
  @CheckForNull
  public V remove(@CheckForNull Object key) {
    return containsKey(key) ? removeFromBothMaps(key) : null;
  }

  @CanIgnoreReturnValue
  @ParametricNullness
  private V removeFromBothMaps(@CheckForNull Object key) {
    // The cast is safe because the callers of this method first check that the key is present.