protected function setIsSimilarToAttribute($values)
    {
        if (is_array($values)) {
            foreach ($values as $key => $value) {
                $product = new self($value);

                $properties = $product->getProperties();

                unset($properties['@context']);

                $properties = array_filter($properties, 'strlen');

                $values[$key] = $properties;
            }
        }

        return $values;
    }