Allow multiple sensitive data in one object

[DanielBadura]

There are situations where an object has mutliple sources of personal data. Let's take a transaction as an example:

class Transaction
{
    public function __construct(
        public TransactionId $transactionId,
        public UserId $senderId,
        #[PersonalData(fallback: 'anon')]
        public string $senderName,
        public UserId $receiverId,
        #[PersonalData(fallback: 'anon')]
        public string $receiverName,
    ) {}
}

Right now, we cannot support to only anonymize only the sender or receiver due to the limitation of only having one DataSubjectId. I thought about adding an identifier to DataSubjectId which could be referenced by PersonalData. This could look like this:

class Transaction
{
    public function __construct(
        public TransactionId $transactionId,
        #[DataSubjectId('sender')]
        public UserId $senderId,
        #[PersonalData(fallback: 'anon', identifier: 'sender')]
        public string $senderName,
        #[DataSubjectId('receiver')]
        public UserId $receiverId,
        #[PersonalData(fallback: 'anon', identifier: 'receiver')]
        public string $receiverName,
    ) {}
}

The attribute changes can be done BC free, not sure about the metadata implementations. But first, we should clarify if this case is valid.