webpack: Can't find module within modulesDirectories

webpack config:

resolve: {
    modulesDirectories: [
      "package_modules",
      "/path/to/app",
      "node_modules"
    ],
]

Option resolve.root is not defined.

Files tree:

/app
|- lib
|   \- index.js
|
\- my_package
      |- package_modules
      |     \- lib
      |          \- index.js
      |
      |- subfolder
      |     \- file_in_subfolder.js
      |
      \ - file_in_package.js

lib/index: export const foo = "foo";

my_package/package_modules/lib/index: export const bar = "bar";

my_package/file_in_package:

import * as obj from "lib";
console.log("lib in package root:", obj);

my_package/subfolder/file_in_subfolder:

import * as obj from "lib";
console.log("lib in package subfolder:", obj);

In console I have:

> lib in package root: { bar: "bar" }
> lib in package subfolder: { foo: "foo" }

Is it correct? I expected that it will be { bar: "bar" } in both cases. Changing import path to lib/index does not help.