Inject Multimap with POST params through an HttpServletRequestWrapper

[berezovskyi]

Depending on the configuration of the JAX-RS application, especially under Jersey, POST parameters may not be readable from the HttpServletRequest and shall be accessed through JAX-RS facilities instead. See https://stackoverflow.com/questions/22376810/unable-to-retrieve-post-data-using-context-httpservletrequest-when-passed-to-o for more details.

While I defined a new interface IJaxTokenStrategy that does not depend on the HttpServletRequest, the key method net.oauth.server.HttpRequestMessage#getParameters does and is outside of our control. Therefore, OAuthRequest.OAuthServletRequestWrapper class has been defined to wrap the original request while substituting the parameter map.

Given that OAuthRequest already provides a reference to the HttpServletRequest, I decided not to remove the newly created interface.

[berezovskyi]

@jadelkhoury this PR will be a bit hard to migrate to https://github.com/eclipse/lyo

Should we merge this one? did you have a chance to test it? I think I wrote the code in response to OAuth failing when POST requests are used. I don't recall the exact problem. Did you ever hit something similar?

[berezovskyi]

Hmm, apparently this PR is superseded by #36?

@jad I don't recall how to reproduce this but I am pretty sure it happened almost out of the box with the Jersey instead of Wink. Did you implement OAuth without Wink and really never hit this problem?