Error message in the log when using server push over HTTP/2

When deploying this[1] example and accessing it using an HTTP/2 supported browser over HTTPS the console logs an an exception that looks like this:

18:27:31,752 ERROR [io.undertow] (default task-2) UT005085: Connection io.undertow.server.protocol.http2.Http2ServerConnection@4899e14e for exchange HttpServerExchange{ GET /servlet-http2/images/payara-logo.jpg request

{accept=[text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8], accept-language=[en-US,en;q=0.9,sv;q=0.8], :authority=[localhost:8443], accept-encoding=[gzip, deflate, br], :path=[/servlet-http2/images/payara-logo.jpg], user-agent=[Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36], :scheme=[https], cookie=[gsScrollPos-810929215=0, gsScrollPos-654=0, gsScrollPos-442=0, gsScrollPos-448=0, gsScrollPos-614=, gsScrollPos-896=0, gsScrollPos-589=, gsScrollPos-577=, gsScrollPos-612=0, gsScrollPos-666=0, gsScrollPos-702=0, gsScrollPos-528=0, gsScrollPos-522=0, gsScrollPos-634=0, gsScrollPos-810=0, gsScrollPos-867=0, gsScrollPos-870=0, gsScrollPos-756=0, gsScrollPos-810927672=0, gsScrollPos-810927716=0, gsScrollPos-810927723=0, gsScrollPos-810927737=0, gsScrollPos-810927743=0, gsScrollPos-810927749=0, gsScrollPos-810927755=0, _ga=GA1.1.1884672541.1538497525, _gid=GA1.1.1746969552.1538497525, _gat=1], :method=[GET], Referer=[https://localhost:8443/servlet-http2/], upgrade-insecure-requests=[1], Host=[localhost:8443]}

response {Last-Modified=[Mon, 01 Oct 2018 15:07:12 GMT], Content-Type=[image/jpeg], Content-Length=[6231], Accept-Ranges=[bytes], Date=[Tue, 02 Oct 2018 16:27:31 GMT], :status=[200]}} was not closed cleanly, forcibly closing connection

The error is verified in both both WildFly 14 and EAP 7.2CD14. The application seems to respond correctly, but above error message is printed in the console.log upon every request.

[1]=https://github.com/javaee-samples/javaee8-samples/tree/master/servlet/http2