private List<String> getDefFileNames() {
        List<String> defFileNames = new ArrayList<>();

        String[] dirNames = defFilesDirectories.split(",");
        List<File> dirs = new ArrayList<>();
        for (String dirName : dirNames) {
            File dir = new File(project.getBasedir(), dirName.trim());
            if (dir.isDirectory() && dir.canRead()) {
                dirs.add(dir);
            }
        }
        for (File dir : dirs) {
            String[] dirFiles = dir.list(new FilenameFilter () {
                public boolean accept(File dir, String name) {
                    return name.endsWith(".def");
                }
            });
            for (String filename : dirFiles) {
                defFileNames.add(dir.toString() + File.separator + filename);
            }
        }
        return defFileNames;
    }
Returns List of all def-files in all defFilesDirectories, including path.
@return The list of def-files.
config-class-plugin/src/main/java/com/yahoo/vespa/ConfigGenMojo.java