8302791: Add specific ClassLoader object to Proxy IllegalArgumentException message

Reviewed-by: alanb, mchung

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

@@ -407,6 +407,11 @@ public abstract class ClassLoader {
         return nid;
     }
 
+    // Returns nameAndId string for exception message printing
+    String nameAndId() {
+        return nameAndId;
+    }
+
     /**
      * Creates a new class loader of the specified name and using the
      * specified parent class loader for delegation.

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

@@ -2663,6 +2663,10 @@ public final class System {
                                                       Continuation continuation) {
                 return StackWalker.newInstance(options, null, contScope, continuation);
             }
+
+            public String getLoaderNameID(ClassLoader loader) {
+                return loader.nameAndId();
+            }
         });
     }
 }

src/java.base/share/classes/java/lang/reflect/Proxy.java

@@ -878,7 +878,7 @@ public class Proxy implements java.io.Serializable {
             }
             if (type != c) {
                 throw new IllegalArgumentException(c.getName() +
-                        " referenced from a method is not visible from class loader");
+                        " referenced from a method is not visible from class loader: " + JLA.getLoaderNameID(ld));
             }
         }
 

src/java.base/share/classes/jdk/internal/access/JavaLangAccess.java

@@ -564,4 +564,9 @@ public interface JavaLangAccess {
     StackWalker newStackWalkerInstance(Set<StackWalker.Option> options,
                                        ContinuationScope contScope,
                                        Continuation continuation);
+    /**
+     * Returns '<loader-name>' @<id> if classloader has a name
+     * explicitly set otherwise <qualified-class-name> @<id>
+     */
+    String getLoaderNameID(ClassLoader loader);
 }