docs: public void warn(Marker marker, String msg, Throwable t) {
          if (!logger.isWarnEnabled(marker))
              return;
          if (instanceofLAL) {
              ((LocationAwareLogger) logger).log(marker, fqcn, LocationAwareLogger.WARN_INT, msg, null, t);
          } else {
              logger.warn(marker, msg, t);
          }
      }