chromium/chrome/test/data/extensions/api_test/keybinding/update/v2_upgrade_reassign/manifest.json

{
  "name": "An action command (modified suggested_key) to test if upgrading from MV2 to MV3 succeeds. (MV3)",
  "version": "1.1",
  "manifest_version": 3,
  "commands": {
    "_execute_action": {
      "suggested_key": "Alt+U"
    }
  },
  "action": {}
}