Setting the response encoding via Filter doesn't work, is always null

When trying to set the character encoding of the HTTP response, the encoding stays null.

This is our filter implementation:

public void doFilter(HttpServletRequest request, HttpServletResponse response, HttpSession session,
FilterChain chain) throws ServletException, IOException
{
System.out.println("encoding is " + request.getCharacterEncoding());
if (request.getCharacterEncoding() == null)

{ request.setCharacterEncoding("UTF-8"); }

if (request.getCharacterEncoding() == null)

{ System.out.println("could not set encoding"); Thread.dumpStack(); }

chain.doFilter(request, response);
}

The stack trace implies that there is only undertow beneath us Some element in the chain has already touched the response.

could not set encoding
java.lang.Exception: Stack trace
at java.lang.Thread.dumpStack(Thread.java:1342)
at de.mdkgmbh.sp.MdkCharacterEncodingFilter.doFilter(MdkCharacterEncodingFilter.java:24)
at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:75)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:56)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:85)
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:59)
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:81)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25)
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:113)
at io.undertow.security.handlers.AuthenticationCallHandler.handleRequest(AuthenticationCallHandler.java:52)
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45)
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:65)
at io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:70)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25)
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:218)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:205)
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:69)
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:134)
at io.undertow.server.HttpHandlers.executeRootHandler(HttpHandlers.java:36)
at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:619)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)

We need a solution for this, as we rely on UTF-8.

We have found no way to configure the listener either, seeing that the old JBoss Web way doesn't work anymore (WFLY-2276)