Made credential_dataset_id required for the issuer and optional for the wallet

Author: awoie

1.1/openid-4-verifiable-credential-issuance-1_1.md

@@ -1385,7 +1385,7 @@ The following parameters are used in the JSON-encoded Credential Response body:
 * `transaction_id`: 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 (#deferred-credential-issuance)). 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.
 * `interval`: REQUIRED if `transaction_id` is present. Contains a positive number that represents the minimum amount of time in seconds that the Wallet SHOULD wait after receiving the response before sending a new request to the Deferred Credential Endpoint. It MUST NOT be used if the `credentials` parameter is present.
 * `notification_id`: OPTIONAL. String identifying one or more Credentials issued in one Credential Response. It MUST be included in the Notification Request as defined in (#notification). It MUST not be used if the `credentials` parameter is not present.
-* `credential_dataset_id`: OPTIONAL.  An opaque string containing the Credential Dataset Identifier associated with the returned Credential(s). This allows Wallets to detect changes to the underlying Credential Dataset across different Credential Responses. This is useful in situations where claim values change over time, such as an updated address, correction of previously issued personal data, or a change in legal or entitlement status (e.g., reaching the age of majority), enabling the Wallet to distinguish between a cryptographic re-issuance of unchanged data and the issuance of a credential containing modified claim values.
+* `credential_dataset_id`: REQUIRED for the Issuer to return. An opaque string containing the Credential Dataset Identifier associated with the returned Credential(s). This allows Wallets to detect changes to the underlying Credential Dataset across different Credential Responses. This is useful in situations where claim values change over time, such as an updated address, correction of previously issued personal data, or a change in legal or entitlement status (e.g., reaching the age of majority), enabling the Wallet to distinguish between a cryptographic re-issuance of unchanged data and the issuance of a credential containing modified claim values. The Wallet MUST NOT expect the `credential_dataset_id` to be always present in the Credential Response.
 
 Additional Credential Response parameters MAY be defined and used. The Wallet MUST ignore any unrecognized parameters.