public final String subString(int offset, int count) {
        if (count < 0) {
            throw new StringIndexOutOfBoundsException(count);
        }
        return new String(buf, offset, count);
        // return text.substring(offset, offset + count);
    }
The value of a literal token, recorded as a string. For integers, leading 0x and 'l' suffixes are suppressed.
src/main/java/com/alibaba/fastjson/parser/JSONReaderScanner.java