I just had a quick look at the code and it seems like the NullPointerException is occurring because you supply null for the parameters. Try an empty map or list depending on what build method of PrettyURLBuilder you are calling.
Another thing I saw: You supply “pretty:adminlogin” for the mapping ID. That is not correct. The prefix pretty: is just used for JSF navigation to identify the action outcome as a PrettyFaces navigation case. The mapping ID is “adminlogin”. So you will have to use this when calling the CustomerRedirector.