XWIKI-11473: Wiki UI extensions are executed with the rights of the current document content author

* Fix execute()

xwiki-platform-core/xwiki-platform-uiextension/xwiki-platform-uiextension-api/src/main/java/org/xwiki/uiextension/internal/WikiUIExtension.java

@@ -178,7 +178,7 @@ public Block execute()
     {
         if (this.renderer != null) {
             try {
-                this.suExecutor.call(new Callable<Block>()
+                return this.suExecutor.call(new Callable<Block>()
                 {
                     @Override
                     public Block call() throws Exception