assertEquals(converter, converter.reverse().reverse());
  }

  // We need to test that apply() does in fact behave like convert().
  @SuppressWarnings("InlineMeInliner")
  public void testApply() {
    assertEquals(LONG_VAL, STR_TO_LONG.apply(STR_VAL));
  }

  private static class StringWrapper {
    private final String value;

    StringWrapper(String value) {
      this.value = value;