phorge-phorge/src/applications/config/option/PhabricatorMailgunConfigOptions.php

<?php

final class PhabricatorMailgunConfigOptions
  extends PhabricatorApplicationConfigOptions {

  public function getName() {
    return pht("Integration with Mailgun");
  }

  public function getDescription() {
    return pht("Configure Mailgun integration.");
  }

  public function getOptions() {
    return array(
      $this->newOption('mailgun.domain', 'string', null)
        ->setLocked(true)
        ->setDescription(
          pht(
            'Mailgun domain name. See https://mailgun.com/cp/domains'))
        ->addExample('mycompany.com', 'Use specific domain'),
      $this->newOption('mailgun.api-key', 'string', null)
        ->setMasked(true)
        ->setDescription(pht('Mailgun API key.')),
    );

  }

}