VoteAccessController::getUserGroups

private function getUserGroups(): array
{
	if (array_key_exists($this->userId, self::$userGroups))
	{
		return self::$userGroups[$this->userId];
	}

	self::$userGroups[$this->userId] = [];

	$groups = UserToGroupTable::getList([
		'select' => ['GROUP_ID'],
		'filter' => [
			'=USER_ID' => $this->userId,
			'@ROLE' => UserToGroupTable::getRolesMember(),
		],
	])->fetchAll();

	self::$userGroups[$this->userId] = array_column($groups, 'GROUP_ID');

	return self::$userGroups[$this->userId];
}