} else {
      checkArgument(!containsValue(value), "value already present: %s", value);
    }
    V oldValue = delegate.put(key, value);
    updateInverseMap(key, containedKey, oldValue, value);
    return oldValue;
  }

  private void updateInverseMap(
      @ParametricNullness K key,
      boolean containedKey,
      @CheckForNull V oldValue,
      @ParametricNullness V newValue) {
    if (containedKey) {