How do Readonly Classes in PHP 8.2+ enforce immutability in Domain-Driven Design (DDD) Data Transfer Objects (DTOs)?

PHP 8.2 Readonly Classes

Marking a class readonly automatically enforces that all declared properties are readonly and prevents dynamic property creation:

readonly class TransferLedgerDTO
{
    public function __construct(
        public string $transactionId,
        public int $amountCents,
        public string $currency,
        public DateTimeImmutable $timestamp
    ) {}
}