code: def clear(target)
        pcl = target_protocol(target) || return
        logger.debug { "Clearing #{pcl.qp} CPR and SCG references..." }
        @database.lazy_loader.suspend do
          pcl.registrations.clear
          pcl.events.each { |event| event.specimen_collection_groups.clear }
        end
      end
docs: Clears the migration protocol CPR and SCG references.
   This action frees up memory for the next iteration, thereby ensuring that migration is an
   O(1) rather than O(n) operation.