public String format(LogRecord record) {

        // if we don't want any other stuff we just return the message
        if (messageOnly) {
            return formatMessage(record);
        }

        String rawMsg = record.getMessage();
        boolean isLogMsg =
            rawMsg.charAt(0) == 'L'
            && rawMsg.charAt(1) == 'O'
            && rawMsg.charAt(2) == 'G'
            && rawMsg.charAt(3) == ':';
        String nameInsert =
            (!isLogMsg)
            ? record.getLevel().getName() + ": "
            : "";
        return (timeStamp(record)
                + nameInsert
                + formatMessage(record)
                + "\n"
                );
    }
Make it possible to log stripped messages
container-core/src/main/java/com/yahoo/container/logging/LogFormatter.java