problems.

1. Not all serviceDiscoveryRegistry will set localInstance, just like ServiceDiscoveryRegistry, it didn't maintain localInstance, it will cause NPE at BubboBootstrap.registerServiceInstance();
   

   dubbo/dubbo-config/dubbo-config-api/src/main/java/org/apache/dubbo/config/bootstrap/DubboBootstrap.java

   Lines 1173 to 1177 in 51d5a88

   	executorRepository.nextScheduledExecutor().scheduleAtFixedRate(() -> {
   	InMemoryWritableMetadataService localMetadataService = (InMemoryWritableMetadataService) WritableMetadataService.getDefaultExtension();
   	localMetadataService.blockUntilUpdated();
   	ServiceInstanceMetadataUtils.refreshMetadataAndInstance();
   	}, 0, ConfigurationUtils.get(METADATA_PUBLISH_DELAY_KEY, DEFAULT_METADATA_PUBLISH_DELAY), TimeUnit.MICROSECONDS);

2. The key which is used to judge instance is update, it should be reset after update process.
   

   dubbo/dubbo-registry/dubbo-registry-api/src/main/java/org/apache/dubbo/registry/client/metadata/ServiceInstanceMetadataUtils.java

   Line 253 in 51d5a88

   instance.getExtendParams().put(INSTANCE_REVISION_UPDATED_KEY, "true");

3. The subclass of ServiceDiscoverty is messed, unify the subclass process about register and update in AbstractServiceDiscovery.