Reviews of a submodule change need to show file change in review

When using a git submodule with a pull request / merge request mechanism enforced (i.e., Bitbucket), when the developer changes the submodule and there is no other change in the parent repository other than pointing to the new merge commit, Collaborator shows no files in the review. Commits are properly listed, but there are no changes to actually review, which is incorrect. Bitbucket, for example, lists the "pointer file" that holds the submodule commit reference. It would be extremely helpful to have Collaborator show this difference as well.