Setting shortenCommandLine "argfile" should not nest a user-passed argfile inside an argfile

When setting shortenCommandLine to argfile (or setting to auto and then triggering the argfile behavior with a long command), VS Code will always put any vmArgs inside an argfile, even if the only VM arg is another argfile. This breaks run configurations that pass a user-generated argfile that still trigger the automatic CLI shortening behavior such as a very long classpath, since argfiles cannot be nested.

Environment

• Operating System: Linux
• JDK version: 17
• Visual Studio Code version: 1.84.0-insider (60182c7e1a666961ded4d0319c154f52d85daf30)
• Java extension version: v0.25.15
• Java Debugger extension version: v0.54.0

Steps To Reproduce

1. Create a trivial Java project ex. a Hello World main method
2. Create an argfile myargs
3. Create launch.json with a corresponding run configuration for the main method. Set shortenCommandLine to argfile to force the argfile behavior (should be equivalent to setting auto and then loading a very long classpath).

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "type": "java",
            "name": "Hello",
            "request": "launch",
            "mainClass": "Hello",
            "vmArgs": "@myargs",
            "shortenCommandLine": "argfile"
        }
    ]
}

4. Attempt to run the main method - this should fail.

Sample project: test-argfile.tar.gz

Current Result

$  /usr/bin/env /path/to/jdk @/tmp/cp_7ifzraqswz8cni6w2z8m6nw3w.argfile Hello 
Error: Could not find or load main class @myargs
Caused by: java.lang.ClassNotFoundException: @myargs

/tmp/cp_7ifzraqswz8cni6w2z8m6nw3w.argfile contents:

@myargs -XX:+ShowCodeDetailsInExceptionMessages -cp "/home/justinw/.vscode-server-insiders/data/User/workspaceStorage/-2d922411/redhat.java/jdt_ws/test-argfile_31bc6c61/bin"

Expected Result

Program should execute and argfiles should not be nested

Additional Informations

Start with the Java launch configuration using vmArgs, shortenCommandLine, and the user-created myargs file, then reproduce the failure with the supplied Hello World steps. Trace how the debugger builds the temporary argfile; done means the program executes without nesting the user-passed argfile.