Expected behaviour or a bug when returning static[] in docblock?

I recently added a static method to an abstract model class, which was setup something like this:

/**
 * @param $ids
 *
 * @return ModelCollection|static[]
 */
 public static function getCollection($ids)
 {
     return ModelCollection::getForIds($ids, static::class);
 }

The idea here is to allow the model extending the abstract class to have a function that returns the right array'd class type when I call:

$extendingModelCollection = ExtendingModel::getCollection($ids)

foreach ($extendingModelCollection as $extendingModel) {
    $extendingModel->someFluentMethod()
        ->anotherFluentMethod();
}

When I then iterate on $extendingModelCollection the $extendingModel inside the loop should be able to understand what methods it has available in auto-complete. The first call to 'someFluentMethod()' auto-completes properly HOWEVER the chained called to 'anotherFluentMethod()' is not recognised. The 'someFluentMethod()' call returns $this, and has @return $this in the docblock.

If I add in a docblock above the foreach to specify the class for $extendingModel, it works as expected. I have also tried changing the docblock to @return ExtendingModel and it doesn't make a difference. It seems there is a disconnect in the fluency when returning static.

So is this expected, even if not desirable? Or is this actually a bug?