final class Service
{
    /**
     * @psalm-var callable(): int
     */
    private $time;

    /**
     * @psalm-param ?callable(): int $time
     */
    public function __construct(?callable $time = null)
    {
        $this->time = $time ?? 'time';
    }

    public function do(): void
    {
        $time = ($this->time)();
    }
}

$service = new Service();

$serviceForTesting = new Service(static fn (): int => 1234567890);

abstract class AggregateRoot
{
    /**
     * @psalm-var list<object>
     */
    private array $events = [];

    /**
     * @psalm-return list<object>
     */
    final public function releaseEvents(): array
    {
▶       [$events, $this->events] = [$this->events, []];

        return $events;
    }

    final protected function raise(object $event, object ...$events): void
    {
        $this->events = [...$this->events, $event, ...$events];
    }
}

null === $stringClientId ? null : ClientId::fromString($stringClientId)

/**
 * @template T of ?string
 * @psalm-param T $id
 * @psalm-return (T is null ? null : self)
 */
public static function fromString(?string $id): ?self
{
    if (null === $id) {
        return null;
    }

    Assert::uuid($id);

    return new self($id);
}

ClientId::fromString($stringClientId)