How to use rule message for pipe pipe syntax

I have a rule class with a message like this

public function message()
{
     return 'The value you have entered is invalid.';
}

But I don't know how to do that

Validator::extend('enum_key', function ($attribute, $value, $parameters, $validator) {
    $enum = $parameters[0] ?? null;

    return (new EnumKey($enum))->passes($attribute, $value);
});

Here is my solution

Validator::extend('enum_key', function ($attribute, $value, $parameters, $validator) {
    $enum = $parameters[0] ?? null;

    return (new EnumKey($enum))->passes($attribute, $value);
}, ((new \ReflectionClass(EnumKey::class))->newInstanceWithoutConstructor())->message());

But as you can see it's messy, what's a cleaner solution?