public class Log {
    private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(Log.class);

    private String stackTrace(Exception cause) {
        if (cause == null)
            return "";
        StringWriter sw = new StringWriter(1024);
        final PrintWriter pw = new PrintWriter(sw);
        cause.printStackTrace(pw);
        pw.flush();
        return sw.toString();
    }

    public void warn(Exception cause, String message) {
        String output = message + "\n" + stackTrace(cause);
        log.warn(output);
    }

    // debug(...), info(...), etc.
}