ATG includes the source for URLHammer, together with source for implementation classes, in:

<ATG10dir>/DAS/src/Java/atg/core/net/

You may want to modify or extend URLHammer for your own testing purposes. However, ATG does not guarantee backward compatibility in future releases of URLHammer. If you make modifications to the code, you should change the class and package names to avoid potential conflicts with future versions we may release.