code: public static String get(String key, Object... args) {
          try {
              String msg = MessageFormat.format(bundle.getString(key), args);
              if (REPLACE_LINESEP) {
                  msg = msg.replace("\n", System.lineSeparator());
              }
              return msg;
          } catch (MissingResourceException e) {
              throw new InternalError("Missing message: " + key, e);
          }
      }
docs: Gets a message from the resource bundle. If necessary, translates "\n",
  the line break string used in the message file, to the system-specific
  line break string.
  
  @param key the message key
  @param args the message arguments