Add support for the prn parameter in the AssertionCredentials. As per: https://developers.google.com/accounts/docs/OAuth2ServiceAccount#additionalclaims
Add support for the prn parameter in the AssertionCredentials.
As per: https://developers.google.com/accounts/docs/OAuth2ServiceAccount#additionalclaims


marcj/google-api-php-client,marcj/google-api-php-client