About Key not specified. after loading nuttx.spk into Sony Spresense

In the Spresense SDK tutorial,
During the boot loader installation, the otkey not specified が is printed twice.

root@ubuntu:~/tools/kconfig-frontends/spresense/sdk#./tools/flash.sh-e~/spresense-binaries-v1.0.000.zip
Update succeeded.
root@ubuntu:~/tools/kconfig-frontends/spresense/sdk# 
root@ubuntu:~/tools/kconfig-frontends/spresense/sdk#./tools/flash.sh-l../firmware/spresense-c/dev/ttyUSB0
>> Install files...
install-b 115200
Install../firmware/spresense/loader.espk
Waiting for XMODEM (CRC or 1K) transfer. Ctrl-X to cancel.
................................................................................................................115984 bytes loaded.
Key not specified.
updater# install-b115200
Install../firmware/spresense/gnssfw.espk
Waiting for XMODEM (CRC or 1K) transfer. Ctrl-X to cancel.
..............................................................................................................................................................................................................................................................................................................................................................................................................................................429984 bytes loaded.
Key not specified.
updater#sync
updater#Restarting the board...
reboot

What does Key not specified refer to?
I thought it was a license key, but there was no such thing.

Hello sample operation verification has been completed, but there will be no problem with future development. I have a question.

The board uses SPRITZER, but Sony's official website has changed its name to SPRESENSE, and since we have already checked the L-chika in Arduino IDE, it will not affect the board.

Thank you for your cooperation.

spresense

2022-09-30 17:42