@Override
    public CharSequence flatten(int logLevel, String tag, String message) {
        return flatten(System.currentTimeMillis(), logLevel, tag, message);
    }
Try to create a message filler if the given parameter is a message parameter.

@return created message filler, or null if the given parameter is not a message parameter
android/android_framework/base/src/main/java/com/elvishew/xlog/flattener/PatternFlattener.java