docs: void handleAddKey() {
  
          String key = m_addKeyInput.getValue();
          if (m_listener.handleAddKey(key)) {
              Notification.show(
                  key.isEmpty()
                  ? m_messages.key(Messages.GUI_NOTIFICATION_MESSAGEBUNDLEEDITOR_EMPTY_KEY_SUCCESSFULLY_ADDED_0)
                  : m_messages.key(Messages.GUI_NOTIFICATION_MESSAGEBUNDLEEDITOR_KEY_SUCCESSFULLY_ADDED_1, key));
          } else {
              CmsMessageBundleEditorTypes.showWarning(
                  m_messages.key(Messages.GUI_NOTIFICATION_MESSAGEBUNDLEEDITOR_KEY_ALREADEY_EXISTS_CAPTION_0),
                  m_messages.key(Messages.GUI_NOTIFICATION_MESSAGEBUNDLEEDITOR_KEY_ALREADEY_EXISTS_DESCRIPTION_1, key));
  
          }
          m_addKeyInput.focus();
          m_addKeyInput.selectAll();
      }