what's the key-id in trusted.gpg.d?

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Hi! I'm a newbie just following "http://wiki.ros.org/noetic/Installati..." have some test.

But there's a warning in shell. [OS: ubuntu 21.04]

[1.3 Set up your keys]

daneil @vpc:~$ curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -
Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).
gpg: no valid OpenPGP data found.

After a few google later. I guess It should be written like this:

$ curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo gpg --no-default-keyring --keyring /etc/apt/trusted.gpg.d/{key-id}.gpg --import -

My question is What's the {key-id}? Thanks!

setup,noetic,ubuntu,install