src/share/classes/javax/swing/plaf/multi/MultiLookAndFeel.java

@@ -292,10 +292,11 @@
  * gracefully if it cannot find a UI.  This class overrides the
  * getUIError method of UIDefaults, which is the method that
  * emits error messages when it cannot find a UI class in the
  * LAF.
  */
+@SuppressWarnings("serial") // Superclass is not serializable across versions
 class MultiUIDefaults extends UIDefaults {
     MultiUIDefaults(int initialCapacity, float loadFactor) {
         super(initialCapacity, loadFactor);
     }
     protected void getUIError(String msg) {