cpix:MacMethod under DeliveryData element

On [https://docs.aws.amazon.com/speke/latest/documentation/content-key-encryption-v2.html](https://docs.aws.amazon.com/speke/latest/documentation/content-key-encryption-v2.html), the example showed for the response includes a cpix:KeyType element under the cpix:MacMethod element which is of pskc:MACMethodType type. Any reason for using cpix:KeyType there ?
See [here](https://dashif.org/docs/CPIX2.1/HTML/Index.html#schema-deliverydata) the schema.

Start by comparing the AWS content-key-encryption-v2 example with the CPIX 2.1 DeliveryData schema linked in the issue. Determine whether cpix:KeyType under cpix:MacMethod is valid and, if not, identify the documentation correction needed; done means the discrepancy has a documented resolution.

Written by the indexing model from the issue text.