public interface NotificationService {
  public void sendNewProjectRequestNotificationToDesigners(String projectId);
  public void sendNewProjectAcceptedNotificationToCustomer(String projectId);
  public void sendNewProjectRejectedNotificationToCustomer(String projectId);
  ...
  // and aboud 30 more methods like that
  // specifying the type of notification and who is going to be sent to
}

public interface NotificationSender {
  public void sendNotification(String projectId);
}

public class NewProjectRequestNotificationSender implements NotificationSender {
  public void sendNotification(String projectId) {
    ...
  }
}

// and many other classes, one for each method in the original interface