@Override
    public ParameterType<?> parameterType() {
        return parameterType;
    }
@Test
    void converter_may_have_non_generic_return_type() throws NoSuchMethodException {
        Method method = JavaParameterTypeDefinitionTest.class.getMethod("convert_capture_group_to_optional_string",
            String.class);
        JavaParameterTypeDefinition definition = new JavaParameterTypeDefinition("", "(.*)", method, false, false,
            false, lookup);
        registry.defineParameterType(definition.parameterType());
        Expression cucumberExpression = new ExpressionFactory(registry)
                .createExpression("{convert_capture_group_to_optional_string}");
        List<Argument<?>> args = cucumberExpression.match("convert_capture_group_to_optional_string");
        assertThat(args.get(0).getValue(), is(Optional.of("convert_capture_group_to_optional_string")));
    }