phorge-phorge/src/applications/config/check/PhabricatorSetupCheckExtraConfig.php

<?php

final class PhabricatorSetupCheckExtraConfig extends PhabricatorSetupCheck {

  protected function executeChecks() {
    $all_keys = PhabricatorEnv::getAllConfigKeys();
    $all_keys = array_keys($all_keys);
    sort($all_keys);

    $defined_keys = PhabricatorApplicationConfigOptions::loadAllOptions();

    foreach ($all_keys as $key) {
      if (isset($defined_keys[$key])) {
        continue;
      }
      $summary = pht("This option is not recognized. It may be misspelled.");
      $message = pht(
        "This configuration option is not recognized. It may be misspelled, ".
        "or it might have existed in an older version of Phabricator. It has ".
        "no effect, and should be corrected or deleted.");

      $this
        ->newIssue('config.unknown.'.$key)
        ->setShortName(pht('Unknown Config'))
        ->setName(pht('Unknown Configuration Option "%s"', $key))
        ->setSummary($summary)
        ->setMessage($message)
        ->addPhabricatorConfig($key);
    }
  }
}