Required fields are not validated
Problem/Motivation
In \Drupal\eca\Entity\Eca::validatePlugin we call $plugin->validateConfigurationForm($form, $form_state); to validate the field values before submitting them and checking for errors. However, this only calls the validateForm callback in the plugin which doesn't call the form API validators and therefore, at least the validation of required fields is not being performed. Maybe even others, but I don't think there are any, that matter in this context.
Proposed resolution
I'm not sure what the best approach would be. We could either iterate over all fields and check ourselves if required fields come with any value. Or we should call a form API callback which does it for us.
Edited by drupalbot