The unsubscribe group to associate with this email.

        :param value: ID of an unsubscribe group
        :type value: GroupId, int, required

def group_id(self, value):
        """The unsubscribe group to associate with this email.

        :param value: ID of an unsubscribe group
        :type value: GroupId, int, required
        """
        if isinstance(value, GroupId):
            self._group_id = value
        else:
            self._group_id = GroupId(value)