@PluginFactory
    public static NameFilter createFilter(
        @PluginAttribute("loggingLevel") final String loggingLevel) {
      // Name required for routing. Error out if it is not set.
      Preconditions.checkNotNull(loggingLevel,
          "loggingLevel must be specified for " + NameFilter.class.getName());

      return new NameFilter(OperationLog.getLoggingLevel(loggingLevel));
    }
A log filter that filters messages coming from the logger with the given names.
It be used as a white list filter or a black list filter.
We apply black list filter on the Loggers used by the log diversion stuff, so that
they don't generate more logs for themselves when they process logs.
White list filter is used for less verbose log collection
ql/src/java/org/apache/hadoop/hive/ql/log/LogDivertAppender.java