code: private void migrateTenantDefinitions() {
          DBService dbservice = DBService.instance();
          List<String> keyspaces = null;
          if (dbservice instanceof ThriftService) {
              keyspaces = ((ThriftService)dbservice).getDoradusKeyspaces();
          } else if (dbservice instanceof CQLService) {
              keyspaces = ((CQLService)dbservice).getDoradusKeyspaces();
          } else {
              return;
          }
          for (String keyspace : keyspaces) {
              migrateTenantDefinition(keyspace);
          }
      }
docs: default database.