code: public SubscriptionEnvelope validateSubscription(String subId, ValidationCallbackInfo validationCallbackRequest) throws ApiException {
          ApiResponse<SubscriptionEnvelope> resp = validateSubscriptionWithHttpInfo(subId, validationCallbackRequest);
          return resp.getData();
      }
docs: Validate Subscription
  Validate Subscription
  @param subId Subscription ID. (required)
  @param validationCallbackRequest Subscription validation callback request (required)
  @return SubscriptionEnvelope
  @throws ApiException If fail to call the API, e.g. server error or cannot deserialize the response body