May this is a bit nit-picky, but i think naming the sample classes e.g. ContactsResource will create confusion about some well defined notions.
A resource is "the intended conceptual target of a hypertext reference"  and has a resource identifier (URL). Obiously the "ContactsResource" class
is not a resource. First of all, the class has no URL (Template) attached and furthermore a resource is more comparable to an object
("today´s weather in chicago" and not "weather" in general).
It is maybe a "ContactsController", which would be nicley fit to the notions in the MVC Pattern (and framework).
 http://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm#sec_5_2 (especially 22.214.171.124)