KERNEL-8038 设计器存在一些静态方法导致最近关闭的模板对象不释放内存

designer-base/src/main/java/com/fr/design/gui/icombobox/FRTreeComboBox.java

@@ -248,11 +248,6 @@ public class FRTreeComboBox extends UIComboBox {
 
     private static TreePopup treePopup;
 
-
-    public static void releaseTreePopup(){
-        treePopup = null;
-    }
-
     private static class FRTreeComboBoxUI extends BasicComboBoxUI implements MouseListener{
         private boolean isRollover = false;