NPE in elytron SPNEGO implementation in exceptional states

21:40:40,640 ERROR [io.undertow.request] (default task-2) UT005023: Exception handling request to /secured-webapp/secure/index.jsp: java.lang.NullPointerException
	at org.wildfly.security.http.impl.SpnegoAuthenticationMechanism.authorizeEstablishedContext(SpnegoAuthenticationMechanism.java:177)
	at org.wildfly.security.http.impl.SpnegoAuthenticationMechanism.evaluateRequest(SpnegoAuthenticationMechanism.java:128)
	at org.wildfly.security.http.util.SetMechanismInformationMechanismFactory$1.evaluateRequest(SetMechanismInformationMechanismFactory.java:115)
	at org.wildfly.security.http.util.SecurityIdentityServerMechanismFactory$1.evaluateRequest(SecurityIdentityServerMechanismFactory.java:77)
	at org.wildfly.security.http.HttpAuthenticator$AuthenticationExchange.authenticate(HttpAuthenticator.java:106)
	at org.wildfly.security.http.HttpAuthenticator$AuthenticationExchange.access$100(HttpAuthenticator.java:90)
	at org.wildfly.security.http.HttpAuthenticator.authenticate(HttpAuthenticator.java:74)
	at org.wildfly.elytron.web.undertow.server.SecurityContextImpl.authenticate(SecurityContextImpl.java:82)
	at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:55)
	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:53)
	at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
	at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
	at io.undertow.servlet.handlers.security.ServletSecurityConstraintHandler.handleRequest(ServletSecurityConstraintHandler.java:59)
	at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
	at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
	at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
	at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:292)
	at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:81)
	at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:138)
	at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:135)
	at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
	at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
	at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1671)
	at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1671)
	at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1671)
	at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1671)
	at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:272)
	at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
	at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:104)
	at io.undertow.server.Connectors.executeRootHandler(Connectors.java:207)
	at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:810)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)