code: public static void w(String tag, String pattern, Object... parameters) {
          w(SUBSYSTEM.MAIN, tag, pattern, parameters);
      }
docs: Send a WARN log message with subsystem {@link SUBSYSTEM#MAIN} as a default one.
  @param tag Used to identify the source of a log message. It usually identifies the class or
  activity where the log call occurs.
  @param pattern The message pattern
  @return