OSLC JSON provider fails to process Link resources compatibly

[berezovskyi]

We'll likely close this as a wontfix because OSLC JSON should be deprecated and removed when possible, but I found a peculiar case when trying to get OSLC JSON support working inside oslc4net.

When the client submits a Link resource and a setter only accepts a Set<Link> type, an exception occurs:

Though I plan to push the try/catch I put around the invoke call to master. Otherwise you get a 400 Bad Request that's not possible to debug.