无JIRA任务 custom_tree + bi.loader，populate的时候会导致“无更多数据”消失

packages/fineui/src/base/combination/loader.js

@@ -248,7 +248,7 @@ export class Loader extends Widget {
         this.button_group.addItems(...arguments);
     }
 
-    _populate(items) {
+    _populate(items, _key, options={}) {
         const o = this.options;
         if (arguments.length === 0 && isFunction(o.itemsCreator)) {
             o.itemsCreator.apply(this, [
@@ -265,6 +265,9 @@ export class Loader extends Widget {
             return false;
         }
         this.options.items = items;
+        if (options.reserveAttributes) {
+            return true;
+        }
         this.times = 1;
         this.count = 0;
         this.count += items.length;