fix: changes to Unstructured metadata do not take effect (#5880)

#### What type of PR is this?
/kind bug
/area core
/milestone 2.16.x

#### What this PR does / why we need it:
修复对 Unstructured 的 metadata 进行更改不会被应用的问题

#### Does this PR introduce a user-facing change?
```release-note
修复插件定义的权限没有在插件详情页显示的问题
```

api/src/main/java/run/halo/app/extension/Unstructured.java

@@ -220,12 +220,7 @@ public class Unstructured implements Extension {
     public static Optional<Map<String, String>> getNestedStringStringMap(Map map,
         String... fields) {
         return getNestedValue(map, fields)
-            .map(labelsObj -> {
-                var labels = (Map) labelsObj;
-                var result = new HashMap<String, String>();
-                labels.forEach((key, value) -> result.put((String) key, (String) value));
-                return result;
-            });
+            .map(labelsObj -> (Map<String, String>) labelsObj);
     }
 
     public static Optional<Instant> getNestedInstant(Map map, String... fields) {

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

@@ -2,6 +2,7 @@ package run.halo.app.extension;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static run.halo.app.extension.MetadataOperator.metadataDeepEquals;
 
@@ -98,10 +99,37 @@ class UnstructuredTest {
     }
 
     @Test
-    void shouldGetFinalizersCorrectly() throws JsonProcessingException, JSONException {
+    void shouldGetFinalizersCorrectly() throws JsonProcessingException {
         var extension = objectMapper.readValue(extensionJson, Unstructured.class);
 
         assertEquals(Set.of("finalizer.1", "finalizer.2"), extension.getMetadata().getFinalizers());
+
+        extension.getMetadata().setFinalizers(Set.of("finalizer.3", "finalizer.4"));
+        assertEquals(Set.of("finalizer.3", "finalizer.4"), extension.getMetadata().getFinalizers());
+    }
+
+    @Test
+    void shouldSetLabelsCorrectly() throws JsonProcessingException {
+        var extension = objectMapper.readValue(extensionJson, Unstructured.class);
+
+        assertEquals(Map.of("category", "fake", "default", "true"),
+            extension.getMetadata().getLabels());
+
+        extension.getMetadata().setLabels(Map.of("category", "fake", "default", "false"));
+        assertEquals(Map.of("category", "fake", "default", "false"),
+            extension.getMetadata().getLabels());
+    }
+
+    @Test
+    void shouldSetAnnotationsCorrectly() throws JsonProcessingException {
+        var extension = objectMapper.readValue(extensionJson, Unstructured.class);
+
+        assertNull(extension.getMetadata().getAnnotations());
+
+        extension.getMetadata()
+            .setAnnotations(Map.of("annotation1", "value1", "annotation2", "value2"));
+        assertEquals(Map.of("annotation1", "value1", "annotation2", "value2"),
+            extension.getMetadata().getAnnotations());
     }
 
     Unstructured createUnstructured() {