refactor: optimize the extension watch parameters to always be of real type (#6180)

#### What type of PR is this?
/kind improvement
/area core
/milestone 2.17.x

#### What this PR does / why we need it:
优化触发 Extension Watch 方法（onAdd/onUpdate/onDelete）时的参数始终为真实类型避免使用时进行类型转换

#### Does this PR introduce a user-facing change?
```release-note
None
```

application/src/main/java/run/halo/app/extension/ReactiveExtensionClientImpl.java

@@ -228,7 +228,7 @@ public class ReactiveExtensionClientImpl implements ReactiveExtensionClient {
             })
             .map(converter::convertTo)
             .flatMap(extStore -> doCreate(extension, extStore.getName(), extStore.getData())
-                .doOnNext(watchers::onAdd)
+                .doOnNext(created -> watchers.onAdd(convertToRealExtension(created)))
             )
             .retryWhen(Retry.backoff(3, Duration.ofMillis(100))
                 // retry when generateName is set
@@ -266,7 +266,9 @@ public class ReactiveExtensionClientImpl implements ReactiveExtensionClient {
             var store = this.converter.convertTo(newJsonExt);
             var updated = doUpdate(extension, store.getName(), store.getVersion(), store.getData());
             if (!onlyStatusChanged) {
-                updated = updated.doOnNext(ext -> watchers.onUpdate(old, ext));
+                updated = updated.doOnNext(ext -> watchers.onUpdate(convertToRealExtension(old),
+                    convertToRealExtension(ext))
+                );
             }
             return updated;
         });
@@ -293,7 +295,7 @@ public class ReactiveExtensionClientImpl implements ReactiveExtensionClient {
         var extensionStore = converter.convertTo(extension);
         return doUpdate(extension, extensionStore.getName(),
             extensionStore.getVersion(), extensionStore.getData()
-        ).doOnNext(watchers::onDelete);
+        ).doOnNext(updated -> watchers.onDelete(convertToRealExtension(extension)));
     }
 
     @Override

application/src/test/java/run/halo/app/extension/ReactiveExtensionClientTest.java

@@ -688,6 +688,47 @@ class ReactiveExtensionClientTest {
 
             verify(watcher, times(1)).onDelete(any());
         }
+
+        @Test
+        void shouldWatchRealType() {
+            var extensionStore = createExtensionStore("/registry/fake.halo.run/fakes/fake");
+            var fake = createFakeExtension("fake", 1L);
+            var unstructured = Unstructured.OBJECT_MAPPER.convertValue(fake, Unstructured.class);
+
+            when(storeClient.fetchByName(extensionStore.getName()))
+                .thenReturn(Mono.just(extensionStore));
+            when(converter.convertTo(any())).thenReturn(extensionStore);
+            when(converter.convertFrom(same(Unstructured.class), any())).thenReturn(unstructured);
+
+            var indexer = mock(Indexer.class);
+            when(indexerFactory.getIndexer(eq(fake.groupVersionKind()))).thenReturn(indexer);
+
+            // on add
+            when(storeClient.create(any(), any())).thenReturn(Mono.just(extensionStore));
+            doNothing().when(watcher).onAdd(any(Extension.class));
+            StepVerifier.create(client.create(unstructured))
+                .expectNext(unstructured)
+                .verifyComplete();
+            verify(watcher, times(1)).onAdd(isA(FakeExtension.class));
+
+            // on update
+            when(storeClient.update(any(), any(), any())).thenReturn(Mono.just(extensionStore));
+
+            doNothing().when(watcher).onUpdate(any(), any());
+            StepVerifier.create(client.update(unstructured))
+                .expectNext(unstructured)
+                .verifyComplete();
+            verify(watcher, times(1))
+                .onUpdate(isA(FakeExtension.class), isA(FakeExtension.class));
+
+            // on delete
+            doNothing().when(watcher).onDelete(any());
+            StepVerifier.create(client.delete(unstructured))
+                .expectNext(unstructured)
+                .verifyComplete();
+            verify(watcher, times(1)).onDelete(isA(FakeExtension.class));
+
+        }
     }
 
 }