# File lib/buildr/packaging/artifact_namespace.rb, line 845
    def group(group_name, *members)
      namespace = (Hash === members.last && members.pop[:namespace]) || :current
      registry[group_name] = lambda do
        artifacts = self.class[namespace].values_at(*members)
        artifacts = artifacts.first if members.size == 1
        artifacts
      end
      self
    end