Support DispatcherType.INCLUDE in DefaultServletHttpRequestHandler

[bergander]

When serving static resources by enabling the DefaultServletHttpRequestHandler you will get an IllegalStateException (Response already commited) error when importing a static resource.

I believe this is caused by the fact that DefaultServletHttpRequestHandler.handleRequest(...) is always calling RequestDispatcher.forward(...) which will set the response to commited. If it were to check the dispatcher type and instead call RequestDispatcher.include(...) when the dispatcher type of the request is set to DispatcherType.INCLUDE, then everything works as expected.

if (request.getDispatcherType() == DispatcherType.INCLUDE) {
	rd.include(request, response);
} else {
	rd.forward(request, response);
}