code: private void migrateMembershipTypes() throws Exception
     {
        Session session = service.getStorageSession();
        try
        {
           if (session.itemExists(membershipTypesStorageOld))
           {
              NodeIterator iterator = ((ExtendedNode)session.getItem(membershipTypesStorageOld)).getNodesLazily();
              MembershipTypeHandlerImpl mth = ((MembershipTypeHandlerImpl)service.getMembershipTypeHandler());
              while (iterator.hasNext())
              {
                 Node oldTypeNode = iterator.nextNode();
                 mth.migrateMembershipType(oldTypeNode);
              }
           }
        }
        finally
        {
           session.logout();
        }
     }
docs: Method for membershipTypes migration.
  @throws Exception