In OpenAPI Schema, productCategoryCpc is defined as NonEmptyString.
However, in Tech Spec, its data type is CpcCode, and its JSON representation should be "encoded as a JSON String". On the other hand, NonEmptyString is defined separately.
Since productCategoryCpc was not defined as NonEmptyString, this definition may cause confusion for app vendors (even now, there are probably applications that respond to this property as an empty string).
It may be better to get a consensus in the community.