[undertow-dev] way to call sendError within AuthMech?

Is there a way to call HttpServletResponse.sendError() within a AuthenticationMechanism? I'm getting the following after calling sendError and returning AuthenticationMechanismOutcome.NOT_AUTHENTICATED java.lang.IllegalStateException: UT010019: Response already commited at io.undertow.servlet.spec.HttpServletResponseImpl.sendError(HttpServletResponseImpl.java:124) at io.undertow.servlet.spec.HttpServletResponseImpl.sendError(HttpServletResponseImpl.java:167) at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:61) at io.undertow.server.handlers.DisableCacheHandler.handleRequest(DisableCacheHandler.java:33) at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43) at io.undertow.security.handlers.AuthenticationConstraintHandler.handleRequest(AuthenticationConstraintHandler.java:51) at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45) -- Bill Burke JBoss, a division of Red Hat http://bill.burkecentral.com