assertThat(outer.converterTo(inner).convert(null)).isNull();
        assertThat(outer.converterTo(inner).reverse().convert(null)).isNull();
      }
    }
  }

  public void testConverter_toString() {
    assertThat(LOWER_HYPHEN.converterTo(UPPER_CAMEL).toString())
        .isEqualTo("LOWER_HYPHEN.converterTo(UPPER_CAMEL)");
  }

  public void testConverter_serialization() {