It appears you're using a
Maven project layout.
Personally, I'm a fan of keeping localization and configuration files in a hierarchy that reflects the packages where they are used.
For instance, if you have a package that deals with persistence, let's say
tld.company.project.repo, then I would put my DB configuration in a file
src/main/config/tld/company/project/repo/db.properties, and add
src/main/config as one of my project's resource folders.
Whatever you do, be consistent.