按官方文档回溯到历史状态，代码执行报错

[BoboOpenSource]

https://java2ai.com/docs/frameworks/graph-core/examples/time-travel，参考这篇文档，编写状态回溯的代码，执行后报错。
代码如下：

NodeAction node1 = state -> Map.of("k1", "v1");
        NodeAction node2 = state -> Map.of("k2", "v2");

        StateGraph workflow = new StateGraph(createKeyStrategyFactory())
                .addNode("node1", node_async(node1))
                .addNode("node2", node_async(node2));

        // 添加基本边
        workflow.addEdge(START, "node1");
        workflow.addEdge("node1", "node2");
        workflow.addEdge("node2", END);

        // 配置持久化
        var memory = new MemorySaver();
        var compileConfig = CompileConfig.builder()
                .saverConfig(SaverConfig.builder()
                        .register("memory", memory)
                        .build())
                .build();

        CompiledGraph compiledGraph = workflow.compile(compileConfig);

        // 使用 thread_id 运行以实现持久化
        var config = RunnableConfig.builder()
                .threadId("customer_123")
                .build();

        Flux<NodeOutput> stream = compiledGraph.fluxStream(ImmutableMap.of(), config);
        stream
                .doOnNext(output -> System.out.println("节点输出: " + output))
                .doOnError(error -> System.err.println("执行错误: " + error))
                .doOnComplete(() -> System.out.println("流完成"))
                .blockLast();

        // 获取所有历史状态
        Collection<StateSnapshot> history = compiledGraph.getStateHistory(config);

        StateSnapshot after_node1_snapshot = new ArrayList<>(history).get(1);

        System.out.println("=============使用node1这个checkpoint创建新分支==============");
        // 从历史状态创建新分支
        var branchConfig = RunnableConfig.builder()
                .threadId("customer_123-branch")  // 新的线程 ID
                .checkPointId(after_node1_snapshot.config().checkPointId().orElse(null))
                .build();

        Flux<NodeOutput> stream_new = compiledGraph.fluxStream(ImmutableMap.of(), branchConfig);
        stream_new
                .doOnNext(output -> System.out.println("节点输出: " + output))
                .doOnError(error -> System.err.println("执行错误: " + error))
                .doOnComplete(() -> System.out.println("流完成"))
                .blockLast();

执行后日志如下：
节点输出: NodeOutput{node=START, state=OverAllState{data={}, resume=false, humanFeedback=null, interruptMessage='null'}}
节点输出: NodeOutput{node=node1, state=OverAllState{data={k1=v1}, resume=false, humanFeedback=null, interruptMessage='null'}}
节点输出: NodeOutput{node=node2, state=OverAllState{data={k1=v1, k2=v2}, resume=false, humanFeedback=null, interruptMessage='null'}}
节点输出: NodeOutput{node=END, state=OverAllState{data={k1=v1, k2=v2}, resume=false, humanFeedback=null, interruptMessage='null'}}
流完成
=============使用node1这个checkpoint创建新分支==============
执行错误: java.util.NoSuchElementException: Checkpoint with id c154b23b-b9ff-4cd9-977a-522159ab6853 not found!
Exception in thread "main" java.util.NoSuchElementException: Checkpoint with id c154b23b-b9ff-4cd9-977a-522159ab6853 not found!
at com.alibaba.cloud.ai.graph.checkpoint.savers.MemorySaver.lambda$put$5(MemorySaver.java:135)
at java.base/java.util.OptionalInt.orElseThrow(OptionalInt.java:273)
at com.alibaba.cloud.ai.graph.checkpoint.savers.MemorySaver.lambda$put$6(MemorySaver.java:134)
at com.alibaba.cloud.ai.graph.checkpoint.savers.MemorySaver.loadOrInitCheckpoints(MemorySaver.java:60)
at com.alibaba.cloud.ai.graph.checkpoint.savers.MemorySaver.put(MemorySaver.java:127)
at com.alibaba.cloud.ai.graph.GraphRunnerContext.addCheckpoint(GraphRunnerContext.java:229)
at com.alibaba.cloud.ai.graph.executor.MainGraphExecutor.handleStartNode(MainGraphExecutor.java:130)
at com.alibaba.cloud.ai.graph.executor.MainGraphExecutor.execute(MainGraphExecutor.java:78)
at com.alibaba.cloud.ai.graph.GraphRunner.lambda$run$0(GraphRunner.java:56)
at reactor.core.publisher.FluxDefer.subscribe(FluxDefer.java:46)
at reactor.core.publisher.Flux.subscribe(Flux.java:8891)
at reactor.core.publisher.Flux.blockLast(Flux.java:2816)
at com.alibaba.cloud.ai.graph.study.GraphStudy.main_恢复到历史状态(GraphStudy.java:159)
at com.alibaba.cloud.ai.graph.study.GraphStudy.main(GraphStudy.java:27)
Suppressed: java.lang.Exception: #block terminated with an error
at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:104)
at reactor.core.publisher.Flux.blockLast(Flux.java:2817)
... 2 more