@Override
  protected void completionCleanup(MasterProcedureEnv env) {
    env.getMasterServices().getClusterSchema().getTableNamespaceManager().setMigrationDone();
  }
Migrate the namespace data to meta table's namespace family while upgrading
hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/MigrateNamespaceTableProcedure.java