Attribute dependency issue in VnfInstanceData and NestedNsInstanceData data types

According Note 1 of the VnfInstanceData data type: "If the overridingVnfdId attribute is present the vnfProfileId attribute shall also be present". It means that either both attributes must be defined or none of them.

Currently, the Open API Specification does not support the attribute dependency as reported in this issue: https://github.com/OAI/OpenAPI-Specification/issues/256.

However, a possible solution is to use an "intermediate" data type called, for instance, vnfdInfo that contains two mandatory attributes, i.e., overridingVnfdId and vnfProfileId. This vnfdInfo "intermediate" data type would be then included as an optional attribute in the VnfInstanceData data model, resolving the problem of the attribute dependency. On the other hand, this solution would make the VnfInstanceData, not in compliance with the SOL005ed431 specification.

The same issue affects the NestedNsInstanceData data type.