// Generate a refreshable OAuth2 credential for authentication.
$oAuth2Credential = (new OAuth2TokenBuilder())->fromFile()->build();
// Construct an API session configured from a properties file and the
// OAuth2 credentials above.
$session = (new AdWordsSessionBuilder())->fromFile()->withOAuth2Credential($oAuth2Credential)->build();
self::runExample(new AdWordsServices(), $session, self::AD_GROUP_ID);