code: @SuppressWarnings("unchecked")
    private List<File> getI18nSourceFiles(File sourceDirectory) throws IOException {
  
      if (i18nSourceFiles == null) {
        if (!sourceDirectory.isDirectory()) {
          i18nSourceFiles = Collections.emptyList();
        }
        else {
          // get list of source files
          String includes = StringUtils.join(SOURCE_FILES_INCLUDES, ",");
          String excludes = FileUtils.getDefaultExcludesAsString();
  
          i18nSourceFiles = FileUtils.getFiles(sourceDirectory, includes, excludes);
        }
      }
  
      return i18nSourceFiles;
    }
docs: Fetches i18n source files from source directory.
  @param sourceDirectory Source directory
  @return a list of XML files
  @throws IOException