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

Reviewed-by: rriggs, chegar

src/java.base/share/classes/java/lang/Throwable.java

@@ -230,6 +230,7 @@ public class Throwable implements Serializable {
      * @serial
      * @since 1.7
      */
+    @SuppressWarnings("serial") // Not statically typed as Serializable
     private List<Throwable> suppressedExceptions = SUPPRESSED_SENTINEL;
 
     /** Message for trying to suppress a null exception. */