public static String formatDatetimeStr(String datetime, StringBuilder digits) {
    if (datetime.contains("+")) {
      String timeZoneStr = datetime.substring(datetime.length() - 6);
      return datetime.substring(0, datetime.length() - 6) + "." + digits + timeZoneStr;
    } else if (datetime.contains("Z")) {
      String timeZoneStr = datetime.substring(datetime.length() - 1);
      return datetime.substring(0, datetime.length() - 1) + "." + digits + timeZoneStr;
    } else {
      String timeZoneStr = "";
      return datetime + "." + digits + timeZoneStr;
    }
  }
Convert from {@link TSStatusCode} to {@link TSStatus}, which has message appended with existing
status message

@param tsStatusCode status type
@param message appending message
iotdb-client/service-rpc/src/main/java/org/apache/iotdb/rpc/RpcUtils.java