Elgg\UpgradeService::getUnprocessedUpgrades PHP Method

    protected function getUnprocessedUpgrades($upgrade_files = null, $processed_upgrades = null)
    {
        if ($upgrade_files === null) {
            $upgrade_files = $this->getUpgradeFiles();
        }
        if ($processed_upgrades === null) {
            $processed_upgrades = $this->config->get('processed_upgrades');
            if (!is_array($processed_upgrades)) {
                $processed_upgrades = array();
            }
        }
        $unprocessed = array_diff($upgrade_files, $processed_upgrades);
        return $unprocessed;
    }