private boolean hasAppenderRefFilter(final Configuration config) {
    for (LoggerConfig loggerConfig : config.getLoggers().values()) {
      boolean isRoot = loggerConfig.getName().isEmpty();
      boolean isGemFire = loggerConfig.getName().startsWith(GEODE_LOGGER_PREFIX);

      if (isRoot || isGemFire) {
        // check for AppenderRef Filter
        for (AppenderRef appenderRef : loggerConfig.getAppenderRefs()) {
          if (appenderRef.getFilter() != null) {
            return true;
          }
        }
      }
    }
    return false;
  }
Name of variable that is set to "true" in log4j2.xml to indicate that it is the default geode
config xml.
geode-log4j/src/main/java/org/apache/geode/logging/log4j/internal/impl/Log4jLoggingProvider.java