public function assignUser($userGroupId, $userId = [])
    {
        $this->groupId = $userGroupId;

        $this->getLogger()->info('Assigning User IDs ' . json_encode($userId) . ' To User Group ID ' . $this->groupId);
        $response = $this->doPost('/group/members/assign/' . $userGroupId, [
            'userId' => $userId
        ]);

        /** @var XiboUserGroup $userGroup */
        $userGroup = $this->hydrate($response);

        return $userGroup;
    }