I have a question about the setup of VSCode using the dev containers extension. When I installed vscode-remote-try-rust provided by Microsoft, “Japanese Language Pack for Visual Studio Code” was automatically detect, and installed on the container side.
I am not sure how this works. I am asking this question purely out of technical interest, but if anyone can help me, please answer.

I have checked the configuration files and scripts, but could not find the relevant part.