public void addToLogger(String loggerName, Level level) {
    LoggerConfig loggerConfig = configuration.getLoggerConfig(loggerName);
    loggerConfig.addAppender(this, level, null);
    context.updateLoggers();
  }
A NullAppender merely exists, it never outputs a message to any device.
ql/src/java/org/apache/hadoop/hive/ql/log/NullAppender.java