String apiKey) throws AuthenticationException,
InvalidRequestException, APIConnectionException, CardException,
APIException {
if ((Stripe.apiKey == null || Stripe.apiKey.length() == 0)
&& (apiKey == null || apiKey.length() == 0)) {
throw new AuthenticationException(
"No API key provided. (HINT: set your API key using 'Stripe.apiKey = <API-KEY>'. "
+ "You can generate API keys from the Stripe web interface. "
+ "See https://stripe.com/api for details or email support@stripe.com if you have questions.");
}