public function getActionKey()
    {
        if ($this->receiver !== null) {
            if ($this->role->getWorkspace() === null) {
                return $this::ACTION_USER;
            } else {
                return $this::ACTION_WORKSPACE_USER;
            }
        } else {
            if ($this->role->getWorkspace() === null) {
                return $this::ACTION_GROUP;
            } else {
                return $this::ACTION_WORKSPACE_GROUP;
            }
        }
    }