@Override
  public IFAState getMatchedState(int stateOrdinal) {
    if (stateOrdinal == 0) {
      return matchedState;
    } else {
      throw new IllegalStateException();
    }
  }
This class is only used for cases not need traceback yet.
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/path/fa/match/StateSingleMatchInfo.java