Class Drupal\\dummyimage\\Form\\DummyimageAdminForm contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (Drupal\\Core\\Form\\ConfigFormBase::getEditableConfigNames)

PHP Fatal error: Class Drupal\\dummyimage\\Form\\DummyimageAdminForm contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (Drupal\\Core\\Form\\ConfigFormBase::getEditableConfigNames) in /var/www/html/drupal8/modules/contrib/dummyimage/src/Form/DummyimageAdminForm.php on line 86