ng-mocks: Bug: A module that is explicitly marked to be kept should be kept even if it's imported in another module that is mocked

Description of the bug

Let’s say that my component under test uses some other components that come from 3rd party library. These components are made available through a module that the 3rd party library also provides. Under the hood, the 3rd party library module is using ReactiveFormsModule.

Now, lets say that my component also does some forms stuff, so I need to use ReactiveFormsModule as well. Therefore I’d want to mock all the components that are coming from the 3rd party library, but keep ReactiveFormsModule. I’d think that I should achieve this behavior via the following:

const deps = MockBuilder()
      .mock(AwesomeLibraryModule) // the 3rd party library module
      .keep(ReactiveFormsModule)
      .build();

This however does not seem to work. The ReactiveFormsModule is not found in the deps.imports. Please see the repro link

A repo with an example of the bug

Link: https://codesandbox.io/s/nostalgic-moore-7sezz5?file=/src/test.spec.ts

Expected vs actual behavior

The ReactiveFormsModule should be included in the deps.imports.