* are.
   */
  public final <C> Converter<A, C> andThen(Converter<B, C> secondConverter) {
    return doAndThen(secondConverter);
  }

  /** Package-private non-final implementation of andThen() so only we can override it. */
  <C> Converter<A, C> doAndThen(Converter<B, C> secondConverter) {
    return new ConverterComposition<>(this, checkNotNull(secondConverter));
  }

   * are.
   */
  public final <C> Converter<A, C> andThen(Converter<B, C> secondConverter) {
    return doAndThen(secondConverter);
  }

  /** Package-private non-final implementation of andThen() so only we can override it. */
  <C> Converter<A, C> doAndThen(Converter<B, C> secondConverter) {
    return new ConverterComposition<>(this, checkNotNull(secondConverter));
  }