Add a source folder as a group, but with any children folders as a folder

I'm working on a Safari web extension which includes a bunch of files and folders in a Resources directory. I need to bundle all of these files and folders, but without a parent "Resources" folder in my app extension. In Xcode it should look like:

Unfortunately I can't find a straightforward way to do this with XcodeGen. If I hardcode each path I can do it, but the contents of this folder can change over time and I'd prefer to just pick up those changes from the file system.

I currently have them hardcoded like this:

    type: app-extension
    platform: iOS
    sources:
      - Sources
      - path: Resources/assets
        type: file
        buildPhase: resources
        group: Resources
      - path: Resources/background.js
        buildPhase: resources
        group: Resources
      - path: Resources/content.js
        buildPhase: resources
        group: Resources
      - path: Resources/manifest.json
        buildPhase: resources
        group: Resources
      - path: Resources/popup.html
        buildPhase: resources
        group: Resources
      - path: Resources/popup.js
        buildPhase: resources
        group: Resources

I'd prefer to be able to just specify the Resources path with some configuration to have it treated like this.

Is there already a way to do this, or is this something that can be easily accomodated?

Start with XcodeGen's source configuration handling and the existing sources entries shown in the issue. Determine how a directory path could include its files while representing child directories as folders, without creating a parent Resources group. Done means a single Resources path produces the requested Xcode structure and continues to include filesystem changes.