code: public String parseErrorMessage(HttpResponse httpResponse, JsonNode jsonNode) {
          // If X_AMZN_ERROR_MESSAGE is present, prefer that. Otherwise check the JSON body.
          final String headerMessage = httpResponse.getHeader(X_AMZN_ERROR_MESSAGE);
          if (headerMessage != null) {
              return headerMessage;
          }
          for (String field : errorMessageJsonLocations) {
              JsonNode value = jsonNode.get(field);
              if (value != null && value.isTextual()) {
                  return value.asText();
              }
          }
          return null;
      }
docs: Parse the error message from the response.
  
  @return Error Code of exceptional response or null if it can't be determined