fix

spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-nacos-discovery/src/main/java/com/alibaba/cloud/nacos/discovery/NacosWatch.java

@@ -22,6 +22,7 @@ import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicLong;
 
 import com.alibaba.cloud.nacos.NacosDiscoveryProperties;
 import com.alibaba.cloud.nacos.NacosServiceManager;
@@ -51,6 +52,8 @@ public class NacosWatch implements ApplicationEventPublisherAware, SmartLifecycl
 
 	private final AtomicBoolean running = new AtomicBoolean(false);
 
+	private final AtomicLong nacosWatchIndex = new AtomicLong(0);
+
 	private ApplicationEventPublisher publisher;
 
 	private NacosServiceManager nacosServiceManager;
@@ -93,9 +96,9 @@ public class NacosWatch implements ApplicationEventPublisherAware, SmartLifecycl
 										instances);
 								instanceOptional.ifPresent(currentInstance -> {
 									resetIfNeeded(currentInstance);
-									publisher.publishEvent(
-											new HeartbeatEvent(this, currentInstance));
 								});
+								publisher.publishEvent(
+										new HeartbeatEvent(this, nacosWatchIndex.getAndIncrement()));
 							}
 						}
 					});