Basically, there are two things :
1. Remove ant configuration in the root POM which copies all *_en.properties to the base ones (webui_en.properties to webui.properties for instance). The copy is not efficient and not a clean way to maintain resource bundle files. What we need is just to keep the base properties file only, the default English language properties should be loaded fallback by the base one normally.
2. Move resource bundle files from src/main/webapp/WEB-INF/classes to src/main/resources. It is more compliant to Maven standard structure.