/// You don't need to pay attention to it, use the configureDataSource
/// specialization instead.
///
+/// \note In future we may want to make the reconfiguration more efficient
+/// by only creating newly configured data and just moving the rest from
+/// the running configuration if they are used in the new configuration
+/// without any parameter change. We could probably do it by passing
+/// the old lists in addition to the new config, but further details are
+/// still to be defined yet. It will surely require changes in the
+/// data source library, too. So, right now, we don't introduce the
+/// possibility in the function interface. If and when we decide to introduce
+/// the optimization, we'll extend the interface.
+///
/// \param config The configuration value to parse. It is in the form
/// as an update from the config manager.
/// \return A map from RR classes to configured lists.