[BUG] 通过nacos同步应用时，当只有一个服务实例，重启时会偶现"com.alibaba.nacos.api.naming.po jo.Instance.getInstanceId()" is null #6143
Description
Is there an existing issue for this?
- I have searched the existing issues
Current Behavior
通过nacos发现服务时，服务只有一个实例的情况下，重启下游服务，会偶现nacos实例为空的情况。导致通过shenyu调用下游服务时报错：
"Can not find healthy upstream url, please check your configuration!"
Expected Behavior
只有一个服务重新完成后，能够正常识别应用。
Steps To Reproduce
- Divide中添加 Selector，通过 nacos 发现服务
- 下游服务只有一个实例
- 重启下游服务时，偶现上面错误
Environment
ShenYu version(s):2.7.0.2Debug logs
错误日志：
[nacos.publisher-com.alibaba.nacos.client.naming.event.InstancesChangeEvent] ERROR
com.alibaba.nacos.common.notify.NotifyCenter - Event callback exception:
java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because the return value of "com.alibaba.nacos.api.naming.po
jo.Instance.getInstanceId()" is null
at org.apache.shenyu.registry.nacos.NacosInstanceRegisterRepository.lambda$compareInstances$3(NacosInstanceRegisterRepository.ja
va:188)
at java.base/java.util.stream.MatchOps$1MatchSink.accept(MatchOps.java:90)
at java.base/java.util.ArrayList$ArrayListSpliterator.tryAdvance(ArrayList.java:1602)
at java.base/java.util.stream.ReferencePipeline.forEachWithCancel(ReferencePipeline.java:129)
at java.base/java.util.stream.AbstractPipeline.copyIntoWithCancel(AbstractPipeline.java:527)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:513)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
at java.base/java.util.stream.MatchOps$MatchOp.evaluateSequential(MatchOps.java:230)
at java.base/java.util.stream.MatchOps$MatchOp.evaluateSequential(MatchOps.java:196)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.anyMatch(ReferencePipeline.java:632)
at org.apache.shenyu.registry.nacos.NacosInstanceRegisterRepository.lambda$compareInstances$4(NacosInstanceRegisterRepository.ja
va:188)
at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:178)
at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
at org.apache.shenyu.registry.nacos.NacosInstanceRegisterRepository.compareInstances(NacosInstanceRegisterRepository.java:189)
at org.apache.shenyu.registry.nacos.NacosInstanceRegisterRepository.lambda$watchInstances$0(NacosInstanceRegisterRepository.java
:135)
at com.alibaba.nacos.client.naming.event.InstancesChangeNotifier.onEvent(InstancesChangeNotifier.java:126)
at com.alibaba.nacos.client.naming.event.InstancesChangeNotifier.onEvent(InstancesChangeNotifier.java:42)
at com.alibaba.nacos.common.notify.DefaultPublisher.lambda$notifySubscriber$0(DefaultPublisher.java:199)
at com.alibaba.nacos.common.notify.DefaultPublisher.notifySubscriber(DefaultPublisher.java:206)
at com.alibaba.nacos.common.notify.DefaultPublisher.receiveEvent(DefaultPublisher.java:190)
at com.alibaba.nacos.common.notify.DefaultPublisher.openEventHandler(DefaultPublisher.java:112)
at com.alibaba.nacos.common.notify.DefaultPublisher.run(DefaultPublisher.java:95)Anything else?
nacos server version:2.2.2
建议修改后的方案：
org/apache/shenyu/registry/nacos/NacosInstanceRegisterRepository.java:188 :
Set<Instance> updatedInstances = currentInstances.stream()
.filter(currentInstance -> currentInstance.getInstanceId() != null &&
previousInstances.stream()
.anyMatch(previousInstance ->
previousInstance.getInstanceId() != null &&
currentInstance.getInstanceId().equals(previousInstance.getInstanceId()) &&
!currentInstance.equals(previousInstance)))
.collect(Collectors.toSet());