code: public String blogAvatar(String blogName, Integer size) {
          String pathExt = size == null ? "" : "/" + size.toString();
          return requestBuilder.getRedirectUrl(JumblrClient.blogPath(blogName, "/avatar" + pathExt));
      }
docs: Get a specific size avatar for a given blog
  @param blogName the avatar URL of the blog
  @param size The size requested
  @return a string representing the URL of the avatar