Need the java file for redirection to login

In my downloaded version of xwiki, I have chosen to authenticate before viewing. In which java file will I find the code where the xwiki makes sure that the user is logged in other wise redirects to the xwiki login page? The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments. WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. www.wipro.com