private int indent(byte[] bytes, int off) {
        bytes[off] = '\n';
        int toIndex = off + 1 + pretty * level;
        Arrays.fill(bytes, off + 1, toIndex, pretty == PRETTY_TAB ? (byte) '\t' : (byte) ' ');
        return toIndex;
    }
A faster alternative that is functionally equivalent to Long.expand(i, 0x0F0F_0F0F_0F0F_0F0FL)
core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF8.java