if (loggerName == null) {
            return event;
        }
        for (final String name : loggerNames) {
            if (loggerName.startsWith(name)) {
                final Level sourceLevel = event.getLevel();
                if (sourceLevel != Level.ERROR) {
                    return event;
                }
                return new Log4jLogEvent.Builder(event).setLevel(Level.WARN).build();
            }
        }