private void stackTraceField(Map<String, Object> map, ILoggingEvent eventObject) {
        IThrowableProxy throwableProxy = eventObject.getThrowableProxy();
        if (throwableProxy != null ) {
            StackTraceElementProxy[] proxyStackTraces = throwableProxy.getStackTraceElementProxyArray();
            if (proxyStackTraces != null && proxyStackTraces.length > 0) {
                StackTraceElement[] callStackTraces = eventObject.getCallerData();
                if (callStackTraces != null && callStackTraces.length > 0) {
                    StackTraceElement lastStack = callStackTraces[0];
                    map.put("_file", lastStack.getFileName());
                    map.put("_line", String.valueOf(lastStack.getLineNumber()));
                }
            }
        }
    }