Class APP\ controllers\grid\ users\author\form\AuthorForm not found

I want to add contributors in OMP 3.4 from a plugin
Code calls the editAuthor($args, $request) function from
In line 352
$authorForm = new AuthorForm($this->getPublication(), $author);
is called which throws an error

Class "APP\controllers\grid\users\author\form\AuthorForm"

If I change the code to call
$authorForm = new \PKP\controllers\grid\users\author\form\PKPAuthorForm($this->getPublication(), $author);
it works.

But this can’t be the solution…
What can I do, any ideas?

Also discussed with hint to this forum here:

Answer was:

Ah , got it , it seems the proper namespace is not included at the top . Also it seems that AuthorGridHandler and the PKPAuthorForm/AuthorForm has been deprecated in 3.4 (see at the top with doc block as @deprecated 3.4). And thats probably why it has not updated with proper namespace.
May be ask in the forum and see anyone know what is the alternative now as this one has been deprecated .

Any ideas somebody?