New features

Introduces the ability to modify the frontend form.

This is a breaking change because of changes to the SubscriberInterface.
The standard form is still available via implementation in SubscriberBase. A submit button with a weight of 999 is also available in this form. When creating a custom Subscriber you have access to this base form in the parents' buildForm() method.

• Issue #3148165 by Project Update Bot: Automated Drupal 9 compatibility fixes.
• Fixed stray space in UI string.
• Fixed failing unit test.

Bugfixes and optimize Drupal 9 support

Add core_version_requirement automated patch generated by Drupal Rector & Project Update Bot

Changelog

• #3147415 by Project Update Bot: Automated Drupal 9 compatibility fixes