In the NuageVsp provider, based on the review comments, we don't have a separate Provider for VPC.
This means that it's impossible to determine if a network offering is for VPC or not, purely based on inspection of the services and providers.
To be able to support Network Offerings for VPC that are not using any service provided by a VPC specific provider like VpcVirtualRouter,
we would like to store this information as part of the offering.
As the response of createNetworkOffering already has a forvpc attribute we use the same attribute as part of the request,
and store the value in the database.