docs: public TranslationMap doImport(File folder) {
          try {
              for (String locale : LOCALES) {
                  TranslationHashMap trMap = new TranslationHashMap(getLocale(locale));
                  trMap.doImport(new FileInputStream(new File(folder, locale + ".txt")));
                  add(trMap);
              }
              postImportHook();
              return this;
          } catch (Exception ex) {
              throw new RuntimeException(ex);
          }
      }