'UT000002: The response has already been started' error when using JASPICAuthenticationMechanism with FORM auth

Issue

• We see errors like the following when using the JASPICAuthenticationMechanism combined with FORM auth in our application:

17:26:36,248 ERROR [io.undertow.request] (default task-1) UT005023: Exception handling request to /app/login.html: java.lang.IllegalStateException: UT000002: The response has already been started
        at io.undertow.server.HttpServerExchange.setStatusCode(HttpServerExchange.java:1406)
        at io.undertow.server.HttpServerExchange.setResponseCode(HttpServerExchange.java:1381)
        at org.wildfly.extension.undertow.security.jaspi.JASPICAuthenticationMechanism.authenticate(JASPICAuthenticationMechanism.java:155)