private static String appendVerticalBorder(String msg) {
        StringBuilder borderedMsgBuilder = new StringBuilder(msg.length() + 10);
        String[] lines = msg.split(SystemCompat.lineSeparator);
        for (int i = 0, N = lines.length; i < N; i++) {
            if (i != 0) {
                borderedMsgBuilder.append(SystemCompat.lineSeparator);
            }
            String line = lines[i];
            borderedMsgBuilder.append(VERTICAL_BORDER_CHAR).append(line);
        }
        return borderedMsgBuilder.toString();
    }
Add {@value #VERTICAL_BORDER_CHAR} to each line of msg.

@param msg the message to add border
@return the message with {@value #VERTICAL_BORDER_CHAR} in the start of each line
android/android_framework/base/src/main/java/com/elvishew/xlog/formatter/border/DefaultBorderFormatter.java