code: @Override
    public String doLayout(ILoggingEvent event) {
  
      // Format message
      String msg = super.doLayout(event).trim();
      // prevent log forging
      msg = preventLogForging(msg);
  
      // Formatting of exception, remove line breaks
      IThrowableProxy throwableProxy = event.getThrowableProxy();
      if (throwableProxy != null) {
        StackTraceElementProxy[] s = throwableProxy.getStackTraceElementProxyArray();
        if (s != null && s.length > 0) {
          // Performance: Initialize StringBuilder with (number of StackTrace-Elements + 1)*50 (+1 for Message)
          StringBuilder sb = new StringBuilder(s.length * BUFFER_PER_LINE);
          sb.append(msg);
  
          int len = s.length;
          for (int i = 0; i < len; i++) {
            sb.append(LINE_SEP).append(s[i]);
          }
          msg = sb.toString();
        }
      }
      return msg + NEWLINE;
    }
docs: Creates formatted String, using conversion pattern.
  
  @param event ILoggingEvent
  @return String Formatted event as string in one line