Issue #3275659: ConnectionBase must implement ContainerFactoryPluginInterface

namespace Drupal\mailgroup;

use Drupal\Component\Plugin\PluginBase;

use Drupal\Core\Plugin\ContainerFactoryPluginInterface;

use Drupal\Core\StringTranslation\StringTranslationTrait;

use Drupal\Core\Logger\LoggerChannelInterface;

use Symfony\Component\DependencyInjection\ContainerInterface;

/**

 * Mail group connection plugin base class.

 */

abstract class ConnectionBase extends PluginBase implements ConnectionInterface {

abstract class ConnectionBase extends PluginBase implements ConnectionInterface, ContainerFactoryPluginInterface {

  use StringTranslationTrait;

  /**