transactionId
OID4VCI: OPTIONAL. String identifying a Deferred Issuance transaction. This parameter is contained in the response if the Credential Issuer cannot immediately issue the Credential. The value is subsequently used to obtain the respective Credential with the Deferred Credential Endpoint (see Section 9). It MUST not be used if the credentials parameter is present. It MUST be invalidated after the Credential for which it was meant has been obtained by the Wallet.