public function transform($dateTime)
    {
        if (null === $dateTime) {
            return '';
        }

        if (!$dateTime instanceof \DateTimeInterface) {
            throw new TransformationFailedException('Expected a \DateTimeInterface.');
        }

        if (!$dateTime instanceof \DateTimeImmutable) {
            $dateTime = clone $dateTime;
        }

        $dateTime = $dateTime->setTimezone(new \DateTimeZone($this->outputTimezone));

        return $dateTime->format($this->generateFormat);
    }