@Override
    protected Iterator<IFATransition> getPreNodeFuzzyMatchTransitionIterator() {
      if (isPrefixMatch) {
        return new SingletonIterator<>(this);
      } else {
        if (tracebackNode == null) {
          return Collections.emptyIterator();
        } else {
          return new SingletonIterator<>(tracebackNode);
        }
      }
    }
The last node represents the prefix match state, and provides the transition access for
patternNodes[rawNodes.length - 1]
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/path/fa/nfa/SimpleNFA.java