protected function variantExtensions()
    {
        $extensions = $this->config->variantExtensions();

        $variants = $this->variantsAttribute();

        if ( ! empty($variants)) {

            foreach ($this->variants() as $variant) {

                $extension = Arr::get($variants, "{$variant}.ext");

                if ($extension) {
                    $extensions[ $variant ] = $extension;
                    continue;
                }
            }
        }

        return $extensions;
    }