private IAppender GetCustomAppender(LogListener listener, LoggerConfiguration confguration) { var customListener = confguration.GetCustomListener(listener.Type); if (customListener != null) { var appender = new CustomAppender(customListener); var patternLayout = new PatternLayout { ConversionPattern = DeafultPatternLayout }; patternLayout.ActivateOptions(); appender.Layout = patternLayout; appender.AddFilter(new LevelRangeFilter { LevelMin = _levelMap[listener.MinLevel], LevelMax = _levelMap[listener.MaxLevel] }); return(appender); } return(null); }