code: public PhotoContext getContext(String photoId, String groupId) throws FlickrException {
          Map<String, Object> parameters = new HashMap<String, Object>();
          parameters.put("method", METHOD_GET_CONTEXT);
  
          parameters.put("photo_id", photoId);
          parameters.put("group_id", groupId);
  
          Response response = transport.get(transport.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 (!elementName.equals("count")) {
                  _log.warn("unsupported element name: " + elementName);
              }
          }
          return photoContext;
      }
docs: Get the context for a photo in the group pool.
  
  This method does not require authentication.
  
  @param photoId
  The photo ID
  @param groupId
  The group ID
  @return The PhotoContext
  @throws FlickrException