JASPICSecureResponseHandler.handleRequest throws NullPointerException when redirecting for CONFIDENTIAL transport guarantee

Issue

*
* We have an application with a CONFIDENTIAL transport-guarantee in its web.xml. When that redirect occurs, we see a NullPointerException:

java.lang.NullPointerException
        at org.wildfly.extension.undertow.security.jaspi.JASPICSecureResponseHandler.handleRequest(JASPICSecureResponseHandler.java:35)
        at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
        at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:285)
        at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:264)
        at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
        at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:175)
        at io.undertow.server.Connectors.executeRootHandler(Connectors.java:202)
        at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:792)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)