In a java GetTax request you can pass a standard street address or if none exists (or is not in the United States Postal Service database) you can pass a latitude / longitude instead.
Replace your address stub with the example below. don't forget to enter the latitude / longitude of the location you want to use.
BaseAddress address = new BaseAddress();
You can view the entire java GetTaxTest Sample here: https://github.com/avadev/AvaTax-Calc-SOAP-java/blob/master/src/GetTaxTest.java