def append_ancestor_enum(enum)
      return enum unless Class === self and superclass < Resource and superclass.introspected?
      anc_enum = yield superclass
      if anc_enum.nil? then
        raise MetadataError.new("#{qp} superclass #{superclass.qp} does not have required metadata")
      end
      enum.union(anc_enum)
    end
def append_ancestor_enum(enum)
      return enum unless Class === self and superclass < Resource and superclass.introspected?
      anc_enum = yield superclass
      if anc_enum.nil? then
        raise MetadataError.new("#{qp} superclass #{superclass.qp} does not have required metadata")
      end
      enum.union(anc_enum)
    end
Appends to the given enumerable the result of evaluating the block given to this method
 on the superclass, if the superclass is also a {Resource} class.

 @param [Enumerable] enum the base collection
 @return [Enumerable] the {Enumerable#union} of the base collection with the superclass
   collection, if applicable