public final char[] sub_chars(int offset, int count) {
        if (count < 0) {
            throw new StringIndexOutOfBoundsException(count);
        }
        
        if (offset == 0) {
            return buf;
        }
        char[] chars = new char[count];
        System.arraycopy(buf, offset, chars, 0, count);
        return chars;
    }
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