Don't resolve globs in files config when using a custom root directory in vite

[igarrido-adalab]

When I run npm run build with Vite (Vite version v4.5.0 in Ubuntu 23.10) using the files setting, it doesn't find any js files.
I'm using a custom Vite configuration as the following vite.config.js:

/ vite.config.js
import { defineConfig } from "vite";
// Concatenate JavaScript files (like former Starter Kit)
import concat from '@vituum/vite-plugin-concat'

export default defineConfig({
  base: "./",
  root: "src",
  publicDir: "../public",
  build: {
    minify: "esbuild",
    outDir: "../docs",
    sourcemap: "inline",
    emptyOutDir: true,
  },
  server: {
    open: "/index.html",
  },
  plugins: [
    concat({
      input: ['main.js'],
      files: {'main.js': ['./js/*.js']}
    }),
  ],
});

The plugin doesn't find any js files inside /src/js/ directory (/src/ from root property and /js/ part is in the glob).