@Override
  protected NotifyRegionMigrationState getInitialState() {
    return NotifyRegionMigrationState.INIT;
  }
A procedure that notifies all DNs of the ongoing region migration procedure.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/procedure/impl/region/NotifyRegionMigrationProcedure.java