8231202: Suppress warnings on non-serializable non-transient instance fields in serializable classes

Reviewed-by: rriggs, chegar

src/java.base/share/classes/java/util/Vector.java

@@ -102,6 +102,7 @@ public class Vector<E>
      *
      * @serial
      */
+    @SuppressWarnings("serial") // Conditionally serializable
     protected Object[] elementData;
 
     /**