JDK 14 RFR of JDK-8230626: Make UnknownFooException strings more informative

[Joe Darcy]

Hello,

Responding to some off-list input from Jon, please review the small 
enhancement for

     JDK-8230626: Make UnknownFooException strings more informative
     http://cr.openjdk.java.net/~darcy/8230626.0/

Patch below; thanks,

-Joe

--- 
old/src/java.compiler/share/classes/javax/lang/model/element/UnknownAnnotationValueException.java 
2019-09-04 14:16:30.437963468 -0700
+++ 
new/src/java.compiler/share/classes/javax/lang/model/element/UnknownAnnotationValueException.java 
2019-09-04 14:16:30.141963468 -0700
@@ -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;
      }
--- 
old/src/java.compiler/share/classes/javax/lang/model/element/UnknownElementException.java 
2019-09-04 14:16:31.153963468 -0700
+++ 
new/src/java.compiler/share/classes/javax/lang/model/element/UnknownElementException.java 
2019-09-04 14:16:30.917963468 -0700
@@ -58,7 +58,7 @@
       * @param p an additional parameter, may be {@code null}
       */
      public UnknownElementException(Element e, Object p) {
-        super("Unknown element: " + e);
+        super("Unknown element: ``" + e + "''");
          element = e;
          this.parameter = p;
      }
--- 
old/src/java.compiler/share/classes/javax/lang/model/type/UnknownTypeException.java 
2019-09-04 14:16:31.777963468 -0700
+++ 
new/src/java.compiler/share/classes/javax/lang/model/type/UnknownTypeException.java 
2019-09-04 14:16:31.545963468 -0700
@@ -58,7 +58,7 @@
       * @param p an additional parameter, may be {@code null}
       */
      public UnknownTypeException(TypeMirror t, Object p) {
-        super("Unknown type: " + t);
+        super("Unknown type: ``" + t + "''");
          type = t;
          this.parameter = p;
      }