Empty Content-type results in request not going through Filters

Hello,

I have filed this issue first to https://github.com/eclipse/jetty.project/issues/2883 thinking it was Jetty's behaviour.

Context :
I'm using Jersey 2 and Jackson to develop a web service on Jetty.
A POST request with an empty Content-type results in a 400 Bad Request response in Jetty without the request going through Request filters.

Issue :
The problem is that I would like to edit the response body but I can't find a way to handle this kind of Exceptions using ExceptionMapper. It seems that the request does not go through Filters nor caught by a generic ExceptionMapper class.

A full demo project (including a test case) can be found at https://github.com/joakime/jetty-issue-2883-jersey-empty-content-type

Thanks