docs: public PhotoContext getContext(String photoId, String userId) throws FlickrException {
          Map<String, Object> parameters = new HashMap<String, Object>();
          parameters.put("method", METHOD_GET_CONTEXT);
  
          parameters.put("photo_id", photoId);
          parameters.put("user_id", userId);
  
          Response response = transportAPI.post(transportAPI.getPath(), parameters, apiKey, sharedSecret);
          if (response.isError()) {
              throw new FlickrException(response.getErrorCode(), response.getErrorMessage());
          }
  
          Collection<Element> payload = response.getPayloadCollection();
          PhotoContext photoContext = new PhotoContext();
          for (Element element : payload) {
              String elementName = element.getTagName();
              if (elementName.equals("prevphoto")) {
                  Photo photo = new Photo();
                  photo.setId(element.getAttribute("id"));
                  photoContext.setPreviousPhoto(photo);
              } else if (elementName.equals("nextphoto")) {
                  Photo photo = new Photo();
                  photo.setId(element.getAttribute("id"));
                  photoContext.setNextPhoto(photo);
              } else {
                  if (logger.isInfoEnabled()) {
                      logger.info("unsupported element name: " + elementName);
                  }
              }
          }
          return photoContext;
      }