8320349: Simplify FileChooserSymLinkTest.java by using single-window testUI

Backport-of: b1cb37432a4b4a10ba68f468e4d988f2a935f198

Author: GoeLin

test/jdk/javax/swing/JFileChooser/FileChooserSymLinkTest.java

@@ -22,14 +22,12 @@
  */
 
 import java.awt.BorderLayout;
-import java.awt.Window;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.beans.PropertyChangeEvent;
 import java.beans.PropertyChangeListener;
 import java.io.File;
 import java.util.Arrays;
-import java.util.List;
 
 import javax.swing.JCheckBox;
 import javax.swing.JFileChooser;
@@ -118,7 +116,7 @@ public static void main(String[] args) throws Exception {
                       .awaitAndCheck();
     }
 
-    private static List<Window> createTestUI() {
+    private static JFrame createTestUI() {
         frame = new JFrame("JFileChooser Symbolic Link test");
         panel = new JPanel(new BorderLayout());
         multiSelection = new JCheckBox("Enable Multi-Selection");
@@ -159,6 +157,6 @@ public void propertyChange(PropertyChangeEvent evt) {
         frame.add(panel, BorderLayout.NORTH);
         frame.add(jfc, BorderLayout.CENTER);
         frame.pack();
-        return List.of(frame);
+        return frame;
     }
 }