yii\rbac\PhpManager::getUserIdsByRole PHP Method

    public function getUserIdsByRole($roleName)
    {
        $result = [];
        foreach ($this->assignments as $userID => $assignments) {
            foreach ($assignments as $userAssignment) {
                if ($userAssignment->roleName === $roleName && $userAssignment->userId == $userID) {
                    $result[] = (string) $userID;
                }
            }
        }
        return $result;
    }