def gid
      URI::GID.build(app: GlobalID.app, model_name: model_name.name.parameterize.to_sym, model_id: id).to_s if id
    end
def gid
      URI::GID.build(app: GlobalID.app, model_name: model_name.name.parameterize.to_sym, model_id: id).to_s if id
    end
Return the Global Identifier for this collection type.
 @return [String] Global Identifier (gid) for this collection_type (e.g. gid://internal/hyrax-collectiontype/3)