Servlet 4 instrument javax.servlet.xxx.mapping request attributes for forward,include and async

[janbartel]

jetty-10

Servlet Spec, 12.3.1 Runtime Discovery of Mappings, pg 12-128

The method getHttpServletMapping() on HttpServletRequest returns an
HttpServletMapping implementation that provides information for the mapping
that caused the current Servlet to be invoked. Please see the javadocs for the
normative specification. Please see sections Section 9.3.1, “Included Request
Parameters” on page 9-101Section 9.4.2, “Forwarded Request Parameters” on
page 9-102 and Section 9.7.2, “Dispatched Request Parameters” on page 9-104 for
relevant request attributes. As with the included and forwarded request parameters,
the HttpServletMapping is not available for servlets that have been obtained with
a call to ServletContext.getNamedDispatcher()

Jetty needs to make the forward attribute javax.servlet.forward.mapping and the include attribute javax.servlet.include.mapping and the AsyncContext javax.servlet.async.mapping attribute available.