remove unuse code (#13036)

Co-authored-by: songxiaosheng <[email protected]>

dubbo-metrics/dubbo-metrics-api/src/main/java/org/apache/dubbo/metrics/event/SimpleMetricsEventMulticaster.java

@@ -40,10 +40,6 @@ public void addListener(MetricsListener<?> listener) {
     @Override
     @SuppressWarnings({"rawtypes", "unchecked"})
     public void publishEvent(MetricsEvent event) {
-        if (event instanceof EmptyEvent) {
-            return;
-        }
-
         if (validateIfApplicationConfigExist(event)) return;
         for (MetricsListener listener : listeners) {
             if (listener.isSupport(event)) {
@@ -75,9 +71,6 @@ public void publishErrorEvent(TimeCounterEvent event) {
     @SuppressWarnings({"rawtypes"})
     private void publishTimeEvent(MetricsEvent event, Consumer<MetricsLifeListener> consumer) {
         if (validateIfApplicationConfigExist(event)) return;
-        if (event instanceof EmptyEvent) {
-            return;
-        }
         if (event instanceof TimeCounterEvent) {
             ((TimeCounterEvent) event).getTimePair().end();
         }

dubbo-metrics/dubbo-metrics-api/src/test/java/org/apache/dubbo/metrics/event/SimpleMetricsEventMulticasterTest.java

@@ -58,16 +58,6 @@ public void onEvent(MetricsEvent event) {
     }
 
 
-    @Test
-    void testPublishEvent() {
-
-        // emptyEvent do nothing
-        MetricsEvent emptyEvent = EmptyEvent.instance();
-        eventMulticaster.publishEvent(emptyEvent);
-        Assertions.assertSame(obj, objects[0]);
-
-    }
-
     @Test
     void testPublishFinishEvent() {