public function transform($raw, array $mapping, $transformed = [])
    {
        foreach ($mapping as $destination => $source) {
            $value = $this->propertyAccessor->isReadable($raw, $source) ?
                $this->propertyAccessor->getValue($raw, $source) : null;
            $this->propertyAccessor->setValue($transformed, $destination, $value);
        }
        return $transformed;
    }