As far as I understand, src/gadgets is for files implementing the gadget interface, src/opensocial is for files implementing the open social interface, and src/common is for utilities common to both gadgets and open-social.
If so, I think file UriGenerator.php should be under src/gadgets: * It users HttpUtil, which is defined in src/gadgets/HttpUtil.php * It is used only in src/gadgets. Not a very important remark, but might make the code easier to understand.
