While going through ATG documentation found one interesting utility. This is Findclass Utility. This will find the .class or JAR file from which a Java class has been loaded. It will also print the CLASS_VERSION information if found.
This utility can be accessed using below URL on your Oracle ATG Web Commerce server.
http://server:port/dyn/dyn/findclass.jhtml
Enter the name of the class in the Class Name field and click Find Class button.
For example ,here I have searched for atg.commerce.order.OrderImpl class.
| Find Class | 
To print debug information append &debug=true to URL. Below is screen capture for OrderImpl with debug information.
| Find Class with Debug Information | 
Class name field accepts class name in below formats.
- atg.commerce.order.OrderImpl
 - atg.commerce.order.OrderImpl.class
 - atg/commerce/order/OrderImpl.class
 - /atg/commerce/order/OrderImpl.java