As filled by @jrieken here microsoft/vscode#86086

• open java-12 dev container
• rename .vscode folder to .vscode-off
• open debug viewlet, select "Run with Java"
• 🐛 no run... there is a progress message about generating configuration and a launch.json file is shown but that is all...

My comment: This is up to the Java extension, they can handle the No Workspace Run however the extension wants. I suggest that the Java extension handles run more gracefully and if the launch.json can get generated the program could be run as well. as part of the experience.

@testforstephen let me know what you think