Add the bean class name to the exception to help identify the problem

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/configuration/branches/CONFIGURATION_390@821988 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/java/org/apache/commons/configuration/beanutils/BeanHelper.java b/src/java/org/apache/commons/configuration/beanutils/BeanHelper.java
index 47ca6cb..5845865 100644
--- a/src/java/org/apache/commons/configuration/beanutils/BeanHelper.java
+++ b/src/java/org/apache/commons/configuration/beanutils/BeanHelper.java
@@ -263,7 +263,7 @@
         if (!PropertyUtils.isWriteable(bean, propName))
         {
             throw new ConfigurationRuntimeException("Property " + propName
-                    + " cannot be set!");
+                    + " cannot be set on " + bean.getClass().getName());
         }
 
         try