Points covered as suggested in #7 are as below.Following points are covered a...

Points covered as suggested in #7 are as below.Following points are covered as suggested in #7

1. In BookAdminEditForm using $this->currentUser() method that is already defined in Parent class FormBase.
2. No need to replace \Drupal::currentUser() call with $this->currentUser() in getDefaultOwnerId() method because its a static method.
3. In FormTestVerticalTabsForm using $this->currentUser() in buildForm() method.

Kindly review a new patch.