No autocomplete for the "submodules" of a library when those included from init.lua

Nobody has claimed this yet.

Dear developers, I've read similar existing issues but didn't find the answer.

I have a library (which I am the developer of) which has this structure:

and `init.lua` is

```lua
local UI = (...) .. '.'

return {
Block = require(UI .. 'Block'),
Image = require(UI .. 'Image'),
Label = require(UI .. 'Label'),
Layout = require(UI .. 'Layout'),
Rectangle = require(UI .. 'Rectangle'),
Stack = require(UI .. 'Stack'),

ImageButton = require(UI .. 'ImageButton'),
TextField = require(UI .. 'TextField'),

utils = require(UI .. 'utils')
}
```

and the rockspec contains this:

```lua
build = {
type = 'builtin',
modules = {
['likelihud'] = 'likelihud/init.lua',
['likelihud.Block'] = 'likelihud/Block.lua',
['likelihud.Image'] = 'likelihud/Image.lua',
['likelihud.Label'] = 'likelihud/Label.lua',
['likelihud.Layout'] = 'likelihud/Layout.lua',
['likelihud.Rectangle'] = 'likelihud/Rectangle.lua',
['likelihud.Stack'] = 'likelihud/Stack.lua',
['likelihud.ImageButton'] = 'likelihud/ImageButton.lua',
['likelihud.TextField'] = 'likelihud/TextField.lua',
['likelihud.utils'] = 'likelihud/utils.lua',
},
}
```
So after install I have

Coc-config:

```json
{
"suggest.noselect": true,
"Lua.workspace.library" : [
"/usr/local/share/lua/5.1"
]
}
```

# The problem

If I write

```lua
local Button = require('likelihud.ImageButton')
```
I get autocomplete for `Button`.

But if instead I do

```lua
local ui = require('likelihud')
```
I get only those fields when I do `ui.`, _but the fields are unknown._ :

So the problem LSP doesn't resolve this `(...) .. '.'` inside `init.lua`. Should I somehow change how `init.lua` provides those files or how to fix that ?

Start with the provided init.lua module and rockspec, then reproduce the two require patterns in LuaLS with the shown workspace.library setting. Trace how dynamic require paths are resolved and how returned table fields receive types; done means ui. offers known, typed fields for the modules exported by init.lua.

Written by the indexing model from the issue text.