code: public static Charge retrieve(String charge) throws StripeException {
      return retrieve(charge, (Map<String, Object>) null, (RequestOptions) null);
    }
docs: Retrieves the details of a charge that has previously been created. Supply the unique charge ID
  that was returned from your previous request, and Stripe will return the corresponding charge
  information. The same information is returned when creating or refunding the charge.