code: public static DefaultAuthenticationTransaction of(final Service service, final Credential... credentials) {
          val creds = sanitizeCredentials(credentials);
          return new DefaultAuthenticationTransaction(service, creds);
      }
docs: Wrap credentials into an authentication transaction, as a factory method,
  and return the final result.
  
  @param service     the service
  @param credentials the credentials
  @return the authentication transaction