If the request URI is the URI of a list page (list of needs, list of
connections), or a need uri, it gets the header that says 'already expired' so that crawlers
re-download these data.
TODO: check the working draft here and see to conformance:
http://www.w3.org/TR/ldp/ TODO: edit according to the latest version of the
spec Not met yet:
If the HTTP 'Accept' header is an RDF MIME type (as listed in the 'produces'
value of the RequestMapping annotation), a redirect to a data uri is sent.