code: public Contacts getList(JinxConstants.ContactFilter filter, int page, int perPage, JinxConstants.ContactSort contactSort) throws JinxException {
      Map<String, String> params = new TreeMap<>();
      params.put("method", "flickr.contacts.getList");
      if (filter != null) {
        params.put("filter", filter.toString());
      }
      if (page > 0) {
        params.put("page", Integer.toString(page));
      }
      if (perPage > 0) {
        params.put("per_page", Integer.toString(perPage));
      }
      if (contactSort != null) {
        params.put("sort", contactSort.toString());
      }
      return jinx.flickrGet(params, Contacts.class);
    }
docs: Get a list of contacts for the calling user.
  <br>
  This method requires authentication with 'read' permission.
  
  @param filter      Optional. Filter the results that are returned.
  @param page        Optional. The page of results to return. If this argument is zero, it defaults to 1.
  @param perPage     Optional. Number of photos to return per page. If this argument is zero, it defaults to 1000. The maximum allowed value is 1000.
  @param contactSort Optional. The order in which to sort the returned contacts. If this argument is null, defaults to name.
  @return object containing contacts matching the parameters.
  @throws JinxException if there are any errors.
  @see <a href="https://www.flickr.com/services/api/flickr.contacts.getList.html">flickr.contacts.getList</a>