Hi,
We are trying to upgrade from JBoss 7 to Wildfly 8.2.1 and encountered this issue. After debugging, we managed to produce a reproducible sample to demonstrate this issue.
In general, calling:

servletContext.getRequestDispatcher("/someServlet;withMatrixParameter=something.jsp").forward(request, response);

will cause HTTP 404, while request the path directly will not have such.
Tracing the code which incorrectly routed to JSP servlet and got HTTP 404.

We suspected this should be a bug in RequestDispatcher implementation, and look for help.

NOTE: we tested in JBoss AS 7.2.0, Glassfish 4.1.1, Tomcat (6.0.45, 7.0.67, 8.0.32, 9.0.0.M3), Jetty (stable-9), both of them works correctly. While tested on Wildfly 8.2.1.Final, 9.0.2.Final and 10.0.0.Final, both of them not working.

Attached the reproducible sample for testing.