public Utf8String concat(Utf8String s) {
        String newOriginalString = str + s.str;
        int totalByteCount = byteCount + s.byteCount;
        int totalCharCount = charCount + s.charCount;
        byte[] newBytes = new byte[totalByteCount];
        System.arraycopy(bytes, byteOffset, newBytes, 0, byteCount);
        System.arraycopy(s.bytes, s.byteOffset, newBytes, byteCount, s.byteCount);
        return new Utf8String(newOriginalString, newBytes, 0, totalByteCount, totalCharCount);
    }
@see java.nio.charset.CharsetEncoder#maxBytesPerChar()
turms-server-common/src/main/java/im/turms/server/common/infra/lang/Utf8String.java