Converter<StringWrapper, Long> converter = first.andThen(STR_TO_LONG);

    assertEquals(LONG_VAL, converter.convert(new StringWrapper(STR_VAL)));
    assertEquals(STR_VAL, converter.reverse().convert(LONG_VAL).value);

    assertEquals("StringWrapper.andThen(string2long)", converter.toString());

    new EqualsTester()
        .addEqualityGroup(first.andThen(STR_TO_LONG), first.andThen(STR_TO_LONG))
        .testEquals();
  }

   * is defined as the function h such that {@code h(a) == g(f(a))} for each {@code a}.
   *
   * <p><b>JRE users and Android users who opt in to library desugaring:</b> use {@code
   * g.compose(f)} or (probably clearer) {@code f.andThen(g)} instead. Note that it is not
   * serializable.
   *
   * @param g the second function to apply
   * @param f the first function to apply
   * @return the composition of {@code f} and {@code g}