--- a/src/java.compiler/share/classes/javax/lang/model/element/UnknownAnnotationValueException.java	Wed Sep 04 13:57:26 2019 -0700
+++ b/src/java.compiler/share/classes/javax/lang/model/element/UnknownAnnotationValueException.java	Wed Sep 04 15:49:25 2019 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -60,7 +60,7 @@
      * @param p an additional parameter, may be {@code null}
      */
     public UnknownAnnotationValueException(AnnotationValue av, Object p) {
-        super("Unknown annotation value: " + av);
+        super("Unknown annotation value: \"" + av + "\"");
         this.av = av;
         this.parameter = p;
     }